Pore-encapsulated catalysts for selective hydrogenolysis of plastic waste

ABSTRACT

Disclosed herein is a catalyst which comprises a silica core having an outer surface and a mesoporous silica shell having an outer surface and an inner surface with the inner surface being inside the outer surface of said mesoporous silica shell proximate to and surrounding the outer surface of said silica core. Wherein the outer surface of the mesoporous silica shell has openings leading to pores within the mesoporous silica shell which extend toward the outer surface of said silica core. The catalyst also includes catalytically active metal nanoparticles positioned within the pores proximate to said core, wherein the catalytic metal nanoparticles comprise about 0.0001 wt % to about 1.0 wt % of the catalyst. Also disclosed are methods of making the catalyst and using it to carry out a process for catalytically hydrogenolysizing a polyolefinic polymer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.63/089,972 filed Oct. 9, 2020. The disclosure of which is incorporatedherein by reference.

GOVERNMENT INTERESTS

This invention was made with government support under DOE Contract No.DE-AC02-07CH11358 awarded by U.S. Department of Energy. The governmenthas certain rights in the invention.

FIELD

The present application is directed to a catalyst and its use for theselective hydrogenolysis of polyolefins.

BACKGROUND

Polymers are irreplaceable in the global economy, with a myriad of usesin packaging, construction, transportation, electronics, and health-careindustries. Many of these applications rely on plastics as inexpensivedisposable materials, which are nonetheless often precisely constructedto confer desired properties essential for the targeted function. Theirmassive-scale manufacture, single-use function, long lifetimes, slowdecomposition rates, and disruption of sensitive ecosystems, however,have created a crisis of plastics waste. Unfortunately, conventionalmechanical recycling methods are limited by considerable technologicaland economic challenges. First, syntheses of many virgin plastics arecurrently less expensive than creating quality recycled materials,because plastics are made on large scale in centralized plants, frominexpensive monomers such as ethylene, in processes that are tightlyintegrated into commodity chemical production. In contrast, wastestreams are widely decentralized and rarely connect with manufacturingconsumer products (aside from recycling). Second, melt-processed wasteplastics frequently have poorer properties than those of the originalmaterials, and this issue is exacerbated with multicomponent mixtures.Thus, recycled plastics are typically limited to applications wherelower-quality materials are acceptable, resulting in minimal economicincentives for waste recovery, sorting, and processing.

Long carbon chains are constructed during olefin polymerizations toachieve desired average lengths and dispersity, stereochemical control,and co-monomer incorporation through catalyst-programmed precision,providing inexpensive plastics with desirable physical and chemicalproperties. The structure/property relationship-guided requirements forhigh quality materials, along with chemical degradation undermelt-reprocessing conditions, contribute to low recycling rates ofhigh-density polyethylene (HDPE, 8.9% US), low-density polyethylene(LDPE) and linear LDPE (LLDPE, 4.3% US, combined) and isotacticpolypropylene (iPP, 0.6% US). Limited recycling, combined with massiveproduction of polyolefins representing more than 50% of the estimated400 million tons of plastics produced worldwide each year, contributesto the disastrous accumulation of plastics everywhere on Earth.

Chemical upcycling, an emerging alternative to the classical recyclingapproach, would use plastic waste as a feedstock for the synthesis ofvalue-added chemicals and materials. Catalytic methods can addfunctional groups to polymer chains through oxidation or C—H bondactivation to create materials with new properties. For example,combination of HDPE and hexane afford alkane liquids via cross-alkanemetathesis (3 d, 150° C.). Alternatively, catalytic hydrogenolysis ofcarbon-carbon bonds can be used to deconstruct the long chains ofpolyolefins into shorter molecules. In a seminal report, anair-sensitive zirconium hydride supported on silica-alumina catalyzeshydrogenolysis of polyethylene to light alkanes (2.5 d, 150° C., 14.5psi H₂). Recently, platinum nanoparticles, supported on strontiumtitanate nanocuboids, were shown to catalyze hydrogenolysis of highdensity polyethylene (HDPE) selectively into uniform liquid alkanes thathave valuable properties as lubricants (4 d, 300° C., 200 psi H₂). Theseapproaches rely on random encounters between catalytic sites andpositions along the macromolecular chains.

The deconstruction of longer polymer chains follows a decay in thenumber-averaged molecular weight (M_(n)) inversely related to the rateof carbon-carbon bond cleavage Assessing and comparing catalystsrequires analysis of the distribution of the species in the reactionmixtures (i.e., the populations). Concurrent generation of all chainlengths by random C—C bond cleavage is undesirable An ideal catalystwould cleaves long chains directly to the desired short chain fragmentsthat are in the liquid range and can yield the desired products over awide range of conversion (FIG. 119 , top).

An example of a catalytic conversion of polymers into liquids isprovided by the hydrogenolysis reaction, in which carbon-carbon bondsare broken at catalytic sites. Pt nanoparticles (NPs) grown on strontiumtitanate nanocuboids through five atomic layer deposition (ALD) cycles(5c-Pt/SrTiO₃), favors cleavage of long chains to lubricant-length highquality liquids and produces only small amounts of gases (<1%). ThisPt-catalyzed hydrogenolysis is a structure-sensitive reaction. Acatalyst with smaller Pt NPs (1.2 nm) made through fewer ALD cycles,produces more small volatile molecules. In less selective hydrogenolysisreactions, the amount of the smallest species (C₁-C₆) that result fromchain end cleavage increase in proportion to the conversion of thelonger chains, as a result of the increased mole fraction of chain ends.

In contrast to the above synthetic methods, nature routinely performsatom-precise deconstructions of flexible macromolecules, such asproteins, cellulose, or even synthetic polymers. The processive modusoperandi of such enzymes involves threading and noncovalent binding ofthe molecular chain in a cleft-like channel containing an active site.This binding cleft engenders conformational and positional specificityonto multiple repeat units of the polymer chain in order to enableprecise cleavage reactions by the active site. Once the cleavage occurs,the smaller molecular mass fragment is released, the polymer threadsfurther into the catalytic pore and is positioned to undergo anothercleavage reaction. These steps are repeated processively, withoutreleasing the polymer, until that entire polymer chain is converted intothe desired uniform species of low molecular mass. A processive polymerdeconstruction may be considered as the reverse of a chain-growthpolymerization, in that reaction mixtures contain only small molecules(monomers or deconstruction products) and high molecular mass polymer.Thus, the product stream from a polymer deconstruction reaction thatobeys a processive mechanism is independent of the chain length of thestarting polymer as well as the conversion.

The rate of PE hydrogenolysis catalyzed by the active sites in smallerPt NPs is higher than that of sites in larger Pt NPs. In contrast, thesimilar rates for the small and large Pt NPs as well as Pt surfaces is ahallmark of structure insensitive reactions. Thus, this qualitativeassessment reveals that PE hydrogenolysis rates are increased withgreater proportions of edge and corner sites compared to facets in thePt NPs. Hydrogenolysis of light linear, branched, and cyclic alkaneshave been demonstrated to be structure sensitive on metal surfaces,whose activity (and selectivity, varies with the exposed single crystalfacet.

Structure sensitivity is often also manifested in terms of selectivity.For example, larger Pt NPs catalyze hydrogenolysis of small hydrocarbonsin solid-gas reactions to give more branched products than linear ones,favoring cleavage of carbon-carbon bonds of secondary carbons over thoseinvolving tertiary carbons. The selectivity of PE hydrogenolysiscatalyzed by small, medium, and larger Pt NPs in mSiO₂/Pt-X/SiO₂ isindependent of the particle size.

To partly address this waste crisis, the upcycling of used polyolefinsinto value-added chemicals would benefit from selective cleavage of thelong chains into a narrow distribution of desired chain lengths, just aspolymer properties and applications are advantaged by highly selectivepolymerizations.

The present application relates to overcoming deficiencies in the art.

SUMMARY

One aspect of the present application relates to a catalyst whichcomprises a silica core having an outer surface and a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said silica core. Theouter surface of the mesoporous silica shell has openings leading topores within the mesoporous silica shell which extend toward the outersurface of said silica core. The catalyst also includes catalyticallyactive metal nanoparticles positioned within the pores proximate to saidcore, wherein the catalytic metal nanoparticles comprise about 0.0001 wt% to about 1.0 wt % of the catalyst.

Another aspect of the present application relates to a process forcatalytically hydrogenolysizing a polyolefinic polymer, which comprisesproviding a polyolefinic polymer and subjecting said polyolefinicpolymer to a hydrogenolysisreaction in the presence of a catalyst tocleave the polymer into hydrocarbon segments. The catalyst comprises asilica core having an outer surface and a mesoporous silica shell havingan outer surface and an inner surface with the inner surface beinginside the outer surface of said mesoporous silica shell proximate toand surrounding the outer surface of said silica core. The outer surfaceof the mesoporous silica shell has openings leading to pores within themesoporous silica shell which extend toward the outer surface of saidsilica core. The catalyst also includes catalytic metal nanoparticlespositioned within the pores proximate to said core to cleave saidpolyolefinic polymer entering said mesoporous silica shell through theopenings into hydrocarbon segments.

A further aspect of the present application relates to a method ofpreparing a catalyst which comprises adding a functional group to asilica core having an outer surface to produce a functionalized silicacore. The functionalized silica core is contacted with a plurality ofcatalytic metal nanoparticles wherein the catalytic metal nanoparticlesadhere to the surface of the functionalized silica core to produce afunctionalized silica core supported catalytic metal nanoparticles. Thefunctionalized silica core supported catalytic metal nanoparticles isthen contacted with a silicon compound to produce a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said functionalizedsilica core supported catalytic metal nanoparticles. The outer surfaceof the mesoporous silica shell has openings leading to pores within themesoporous silica shell which extend toward the outer surface of saidfunctionalized silica core supported catalytic metal nanoparticles.

This architecture and the catalytic process is further illustrated byFIG. 1 which shows in (a) the processive process through which manyenzymes deconstruct large macromolecules. First, the polymer threads andbinds into the catalytic pore or cleft. A catalytic cleavage reaction atthe active site (represented by a pair of scissors) releases a lowmolecular mass fragment. The macromolecule then threads further into thepore to repeat the process. An analogous mechanism proposed for themSiO₂/Pt/SiO₂ catalyst is shown in (b) of FIG. 1 , where SiO₂-supportedPt nanoparticles are located at the end of nanopores in the mesoporousSiO₂ (mSiO₂) shell.

The present application provides an artificial processive catalyst forpolyethylene hydrogenolysis from chemically and thermally robustinorganic materials. The key design elements include (1) pores that aresufficiently narrow to support headfirst adsorption of a polymer chainin an induced straightened conformation, (2) a catalyst positioned nearthe end of the pore that selectively cleaves one type of bond at aregular interval from the chain end, and (3) pore size, structure, andchemistry that permits the desorption and release of the small-moleculeproducts.

To design a processive catalytic process for upcycling of polyethylene,the adsorption and dynamics of HDPE and small hydrocarbons in poroussilicas were first spectroscopically investigated. These studiesidentified the pore characteristics required by design element (1) anddemonstrated that long polymer chains bind preferentially to the surfaceover small hydrocarbons; design element (3). A functioning catalyst wasthen constructed by positioning active sites for carbon-carbon bondhydrogenolysis, namely Pt nanoparticles, at the closed ends of thesepores to achieve the design element (2). In this catalytic process,small molecules desorb and exit the pore as they are cut from thepolymer end, allowing the catalyst to processively digest entire chainsof HDPE.

In contrast with traditional synthetic catalytic systems, enzymes areable to reliably produce atom-precise fragments from largemacromolecules by utilizing a processive mechanism. Using solid-statenuclear magnetic resonance (NMR) spectroscopy it was shown thatmesoporous silica materials can grasp polyethylene chains thatnonetheless remain mobile. These properties are central requirements forachieving processivity in a catalytic process. Inspired by this result,a hydrogenolysis catalyst housing Pt nanoparticles at the base of silicamesopores was designed and synthesized. The processive polymerdeconstruction, realized by this catalyst, leads to a narrowPt-catalyzed distribution of short chain products from PE and opens anew avenue to waste polymer upcycling. The oily product could beseparated into fuels, solvents, and lubricating oil. In fact, themSiO₂/Pt/SiO₂ catalyst is active for hydrogenolysis of post-consumerHDPE, including multilayer plastics films obtained from single-usegrocery-style shopping bags. The hydrogenolysis of isotacticpolypropylene (iPP) is catalyzed by mSiO₂/Pt/SiO₂ to a liquid productdistribution (79% yield) from C₉-C₁₈.

The features of these conversions highlight the potential benefits ofprocessive catalytic transformation for upcycling single-use plastics.It was speculated that the architectural motifs of the processivecatalyst, such as pore diameter and length, could be designed to‘dial-in’ the center-point of the catalyst-generated productdistribution. Moreover, the standard deviation of product distributionswill be affected by the balance between polymer and product bindingthermodynamics and kinetic properties of carbon-carbon bond-cleavingsites. The modified architecture of a processive catalyst could alsooffer enhancement of catalytic rates by holding mobile macromolecules ina desired position with respect to catalytic sites. Finally, theplacement of a catalytic site within a narrow pore may provide astrategy to exclude certain large, non-linear molecules, such as lowdensity polyethylene or linear low density polyethylene. These featuresand the processive mechanism, however, will likely be affected by ratesof adsorption and desorption of chains in the pores, migration of chainsthrough the pores, and carbon-carbon bond cleavage steps, all of whichwill be affected by the properties of the polymer. Likely, accessing ahigh degree of processive behavior to selectively produce the desiredproducts will involve a degree matching of catalyst and polymerarchitectures.

Selective hydrogenolysis of polyethylene and isotactic polypropylene tonarrow distributions of hydrocarbon oligomers is catalyzed by sphericalmesoporous silica shell/active platinum NP/silica core (mSiO₂/Pt/SiO₂)materials. This catalytic architecture creates linear, radial-orientedwells with Pt NPs located solely at the bottom, requiring thehydrocarbon chains to adopt a zig-zag, all-anti conformation as theydiffuse through the mesopores to access the catalytic sites. Theinfluence of the catalytic architecture upon the products' length anddistribution could result from a number of factors, including chainadsorption phenomena in the pores, rates of chain diffusion and rates ofcarbon-carbon bond cleavage via exposed active sites, and/or the poretemplating a specific conformation of the chains.

This possibility, that the dimensions of Pt NPs affect the product chainlength, is investigated in the present disclosure, which also examinesthe influence of Pt NP size on rates and selectivity in hydrogenolysisof polyethylene catalyzed by the mSiO₂/Pt-X/SiO₂ architecture (where Xis the mean Pt NP diameter). We infer that hydrogenolysis catalysisusing mSiO₂/Pt-X/SiO₂ is a structure-sensitive catalytic reaction

The synthesis of smaller (1.7 nm), intermediate (2.9 nm), and larger(5.0 nm) Pt NPs in the identical mSiO₂/Pt—X/SiO₂ architecture provides afamily of efficient, highly active, and highly selective catalysts withcharacteristic features and excellent behavior, across the three Pt NPsizes, in polyethylene hydrogenolysis. The smallest Pt NP is smallerthan the 2.4 nm diameter of the mesopore in mSiO₂/Pt—X/SiO₂, while thelargest Pt NP is larger than the pore diameter. The conversionscatalyzed by these catalysts proceed in stages. This distribution istemplated by the mSiO₂/Pt—X/SiO₂ architecture, rather than by the sizeof the Pt NPs. Adsorption of PE chains into mesopores limitsconformations to affect the average product chain length. Thispore-templated cleavage phenomenon was also observed inmSiO₂/Pt-5.0/SiO₂-catalyzed hydrogenolysis of PE at 250° C., whichshowed features consistent with a processive mechanism. Thus, thepore-templated carbon-carbon bond cleavage, which is a component of theprocessive mechanism, also functions in related processes with a lowdegree of processivity. The present disclosure also indicates that thesize of the exposed Pt surface, dictated either by Pt NP size or porediameter of the mesoporous shell, is unlikely to be responsible forselecting the average chain-length of the product.

Thus, mSiO₂/Pt—X/SiO₂ is not only selective for hydrogenolysis of PE towaxes but also remarkably selective for hydrogenolysis of PE in thepresence of a large amount of C₂₃-centered waxes. The PE hydrogenolysisoccur faster with smaller Pt NPs than with larger ones, corresponding toan increase in catalytic rate without significantly diminishingselectivity. The selectivity of PE hydrogenolysis catalyzed by small,medium, and larger Pt NPs in mSiO₂/Pt-X/SiO₂ is independent of theparticle size.

Finally, another beneficial aspect of the localization of platinumnanoparticles in the mesoporous silica/platinum/silica core architectureis that the production of low value gas products (methane, ethane,propane, butane) is limited. Those gases form at early stages of thehydrogenolysis conversion, but then polymer chains are transformed withnearly perfect selectivity into the desired wax and liquid products forthe remainder of the catalytic experiment before the total consumptionof polymer chains. The catalytic architecture appears to be responsiblefor this behavior, which is observed with small, medium, and large Ptnanoparticles in the architecture, but not without the presence of themesoporous silica shell overcoating on platinum nanoparticles. Thus, thebehavior leads to high selectivity for the desired liquid and waxproducts.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 A-B shows the processive process through which many enzymesdeconstruct large macromolecules is depicted (a) and an analogousmechanism proposed for the mSiO₂/Pt/SiO₂ catalyst (b).

FIGS. 2 A-C shows the room temperature ¹³C MAS NMR spectra of *PE(M_(n)=130 kDa) adsorbed onto commercial silica gel (a) and mSiO₂ (b),an analogous spectrum of natural abundance PE (M_(n)=7 kDa) on mSiO₂ isshown in (c), spatial assignments are depicted on the right.

FIGS. 3 A-D shows the (a) Representative ¹³C EXSY spectrum (93° C.,t_(mix)=2 s) showing the exchange between the polymer inside the poreand at the pore mouth (black square). (b) Exchange cross-peak build-upcurves for temperatures of 72, 93, and 114° C. (c) D_(eff) as a functionof t_(mix). (d) Representative Arrhenius plot (t_(mix)=2 s) used todetermine the activation energy for the intra-pore diffusion.

FIGS. 4 A-B shows the bright-field TEM (a) and HAADF-STEM (b) images ofthe mSiO₂/Pt/SiO₂ catalyst, the small dark dots in (a) and bright dotsin (b) are Pt nanoparticles that are supported on the surface ofspherical SiO₂ core and located at the terminal end of the linearchannel of mSiO₂ shell.

FIGS. 5 A-C shows the (a) Combined table of HT-GPC and GC data showingconversion-independent product distributions from mSiO₂/Pt/SiO₂ andconversion-dependent product distributions obtained with Pt/SiO₂, (b)HT-GPC analysis of molecular mass and distributions of HDPE before andafter hydrogenolysis using mSiO₂/Pt/SiO₂ or Pt/SiO₂, and (c) combineddistributions of the gas and liquid products obtained from thehydrogenolysis of HDPE using mSiO₂/Pt/SiO₂ (top) or Pt/SiO₂ (bottom).

FIG. 6 shows the product distributions of liquid products obtained fromthe hydrogenolysis of HDPE at full conversion at 300° C. under 200 psiH₂ for 24 h using mSiO₂/Pt/SiO₂ (0.004 wt % Pt) with 1.7, 2.4, and 3.5nm diameter pore sizes.

FIGS. 7 A-C shows the TEM images of the mSiO₂ (a) and Stöber silicas of50 (b) and 200 (c) nm in diameter.

FIGS. 8 A-B shows the enlarged view of the TEM images of the mSiO₂.

FIGS. 9 A-C shows the TEM images of 127 nm Stöber silica spheres (a),the Pt/SiO₂ particles (b), and the mSiO₂/Pt/SiO₂ catalyst with 2.4 nmpore diameter in the mesoporous shell (c).

FIGS. 10 A-B shows the TEM images of the mSiO₂/Pt/SiO₂ catalyst with 1.7(a) and 3.5 nm (b) pore diameter in the mesoporous shell.

FIGS. 11 A-C shows the TEM images of Pt/SBA-15 (a), Pt/MCM-41 (b), andNiMo/γ-Al₂O₃ (c). The diameters of Pt nanoparticles are 6.5±1.2 and2.8±1.1 nm for Pt/SBA-15 and Pt/MCM-41, respectively.

FIG. 12 shows the typical low angle diffraction peak of MCM-type mSiO₂.

FIG. 13 shows the N₂ sorption isotherms of the mSiO₂, Davisil silicagel, and the 50 and 200 nm Stöber silica spheres.

FIG. 14 shows the pore size distributions of the mSiO₂, Davisil silica,and 50 and 200 nm Stöber silica spheres, with adsorption branch.

FIG. 15 shows the N₂ sorption isotherms of the mSiO₂/Pt/SiO₂,mSiO₂/SiO₂, and the 127 nm Stöber silica spheres.

FIG. 16 shows the pore size distributions of the mSiO₂/Pt/SiO₂,mSiO₂/SiO₂, and the 127 nm Stöber silica spheres, with adsorptionbranch.

FIG. 17 shows the N₂ sorption isotherms of the mSiO₂/Pt/SiO₂ catalystswith pore diameters of 1.7, 2.4, and 3.5 nm.

FIG. 18 shows the pore size distribution of the mSiO₂/Pt/SiO₂ catalystswith pore diameters of 1.7, 2.4, and 3.5 nm, with adsorption branch.

FIG. 19 shows the N₂ sorption isotherms of the Pt/SBA-15, Pt/MCM-41, andNiMo/γ-Al₂O₃.

FIG. 20 shows the pore size distribution of the Pt/SBA-15, Pt/MCM-41,and NiMo/γ-Al₂O₃, with adsorption branch.

FIG. 21 shows the GC-MS trace of RESTEK ASTM D2887-12 STANDARD used toidentify and quantify carbon numbers of species in samples fromcatalytic hydrogenolysis experiments.

FIG. 22 shows the response factor in GC-MS chromatogram plotted againstcarbon number. The linear least squares regression analyses are used toestimate the response integrated intensity for carbon species notpresent in ASTM standard by interpolating within the ranges C₅-C₂₀ andC₂₀-C₄₀, which show linearity.

FIG. 23 shows the SimDist GC-FID of a standard mixture of saturatedlinear alkanes (D2287—Restek) dissolved in dichloromethane. The baselineis flat, showing that column or acquisition conditions inherently leadto flat baselines with this column and method (e.g., no columnbleeding), and chromatograms below with non-flat baselines areattributed to samples containing poorly resolved branched isomers.

FIG. 24 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE and H₂ (200 psi) using mSiO₂/Pt/SiO₂(0.042 Pt wt/silica wt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt% in the reactor for 6 h at 250° C., vented and sampled at 250° C., givea yield of volatile species corresponding to 3.35% of the starting HDPE.

FIG. 25 shows the GC-MS of hydrogenolysis oil products (3.42% yield)from reaction of HDPE using mSiO₂/Pt/SiO₂ (0.042 Pt wt/silica wt %) ascatalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactor for 6 h at250° C. under H₂ (200 psi), isolated by extraction of the solid reactionmixture with methylene chloride at 80° C. from the reaction that wasvented at 250° C.

FIG. 26 shows the carbon number distribution for the hydrogenolysisreaction of HDPE using mSiO₂/Pt/SiO₂ (0.042 Pt wt/silica wt %) ascatalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactor for 6 h at250° C. under H₂ (200 psi).

FIG. 27 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE and H₂ (200 psi) using Pt/SiO₂ (0.478 Ptwt/silica wt %) as catalyst, conditions: 0.00099 Pt wt/HDPE wt % in thereactor for 6 h at 250° C. under H₂ (200 psi), yielding volatile speciescorresponding to 3.99% of the starting HDPE.

FIG. 28 shows the GC-MS of hydrogenolysis oil products (3.99% yield)from reaction of HDPE and H₂ (200 psi) using Pt/SiO₂ (0.478 Pt wt/silicawt %) as catalyst, conditions: 0.00099 Pt wt/HDPE wt % in the reactorfor 6 h at 250° C. under H₂ (200 psi), and the product was isolated byextraction of the solid reaction mixture with methylene chloride at 80°C.

FIG. 29 shows the carbon number distribution for the hydrogenolysisreactions of HDPE using Pt/SiO₂ (0.478 Pt wt/silica wt %) as catalyst,conditions: 0.00099 Pt wt/HDPE wt % in the reactor for 6 h at 250° C.under H₂ (200 psi).

FIG. 30 shows the comparison of distributions of carbon numbers forhydrogenolysis reactions using the two catalysts, mSiO₂/Pt/SiO₂ andPt/SiO₂, at 250° C. under H₂ (200 psi) after 6 h, obtained fromyield-weighted contributions of headspace and isolated oil, with the twocomponents' distributions analyzed by GC-MS.

FIG. 31 shows the GC-MS trace of the sampled headspace (corresponding to0.24% of the starting HDPE) for the hydrogenolysis reaction of HDPEusing mSiO₂/Pt/SiO₂ (0.040 Pt wt/silica wt %) as catalyst, conditions:0.00087 Pt wt/HDPE wt % in the reactor for 6 h at 250° C. under H₂ (at200 psi), vented and sampled at 25° C.

FIG. 32 shows the GC-MS of oil products (5.09% yield) fromhydrogenolysis of HDPE using mSiO₂/Pt/SiO₂ (0.040 Pt wt/silica wt %) ascatalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactor for 6 h at250° C. under H₂ (200 psi), and the product was isolated by extractionof the solid reaction mixture with methylene chloride at 80° C. from thereactor that was vented at 25° C.

FIG. 33 shows the carbon number distribution for the hydrogenolysisreaction of HDPE, using mSiO₂/Pt/SiO₂ (0.040 Pt wt/silica wt %) ascatalyst, from yield-weighted contributions of headspace and isolatedoil, with the two components' distributions analyzed by GC-MS shown inFIGS. 31 and 32 . Conditions: 0.00087 Pt wt/HDPE wt % in the reactor for6 h at 250° C. under H₂ (200 psi).

FIG. 34 shows the SimDist GC-FID of hydrogenolysis oil products (5.09%yield) from reaction of HDPE using mSiO₂/Pt/SiO₂ (0.040 Pt wt/silica wt%) as catalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactor for 6h at 250° C. and H₂ (200 psi). Product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C. The reactor wasvented at 25° C. at the end of the reaction.

FIG. 35 shows the GC-MS trace of the sampled headspace (corresponding to1.9% of the starting HDPE) for the hydrogenolysis reaction of HDPE usingPt/SiO₂ (0.59 Pt wt/silica wt %) as catalyst, conditions: 0.0018 Ptwt/HDPE wt % in the reactor for 6 h at 250° C. under H₂ (200 psi),vented and sampled at 25° C.

FIG. 36 shows the GC-MS of hydrogenolysis oil products (11.6% yield)from reaction of HDPE using Pt/SiO₂ (0.59 Pt wt/silica wt %) ascatalyst, conditions: 0.0018 Pt wt/HDPE wt % in the reactor for 6 h at250° C. under H₂ (200 psi), with the product isolated by extraction ofthe solid reaction mixture with methylene chloride at 80° C. from thereactor vented at 25° C.

FIG. 37 shows the carbon number distribution from the hydrogenolysisreaction of HDPE, using Pt/SiO₂ as catalyst (0.59 Pt wt/silica wt %),from yield-weighted contributions of headspace and isolated oil, withthe two components' distributions analyzed by GC-MS shown in FIGS. 35and 36 . Conditions: with 0.0018 Pt wt/HDPE wt % in the reactor for 6 hat 250° C. under H₂ (200 psi).

FIG. 38 shows the comparison of distributions of carbon numbers forhydrogenolysis reactions using the two catalysts, mSiO₂/Pt/SiO₂ andPt/SiO₂ for 6 h at 250° C. under H₂ (200 psi), obtained fromyield-weighted contributions of headspace and isolated oil, with the twocomponents' distributions analyzed by GC-MS.

FIG. 39 shows the GC-MS trace of the volatile products (1.9% yield) froma control experiment. The sample was obtained by heating HDPE for 6 hunder H₂ (200 psi) in the presence of mSiO₂/SiO₂ (Pt-free), and then theheadspace of the reactor was vented and sampled at 250° C.

FIG. 40 shows the GC-MS trace of the oils (1.03% yield) obtained from acontrol experiment by heating HDPE in the presence of mSiO₂/SiO₂ for 6 hat 250° C. under H₂ (200 psi), venting the reactor at 250° C. Extractionof the oils was accomplished using methylene chloride heated at 80° C.

FIG. 41 shows the Carbon number distribution for products from thecontrol experiment, in which HDPE and mSiO₂/SiO₂ were heated for 6 h at250° C. under H₂ (200 psi), obtained from yield-weighted contributionsof headspace and isolated oil.

FIG. 42 shows the GC-MS trace of the volatile products (0.61% yield)from a control experiment performed in the absence of platinum or silicamaterials. The sample was obtained by heating HDPE for 6 h at 250° C.under H₂ (200 psi) without any additional catalyst, and then theheadspace of the reactor was vented and sampled at 250° C.

FIG. 43 shows the GC-MS trace of the oil products (0.68% yield) obtainedfrom a control experiment performed in the absence of platinum or silicamaterials. The sample was obtained by heating HDPE for 6 h at 250° C.under H₂ (200 psi) without any additional catalyst, and then theheadspace of the reactor was vented, and the residue was extracted withmethylene chloride at 80° C.

FIG. 44 shows the carbon number distribution for products from thecontrol experiment, in which HDPE was heated for 6 h at 250° C. under H₂(200 psi), obtained from yield-weighted contributions of headspace andisolated oil.

FIG. 45 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) usingmSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %) as catalyst, conditions: 0.0013Pt wt/HDPE wt % in the reactor for 24 h at 250° C. under H₂ (200 psi),cooled to room temperature and vented, give a yield of volatile speciescorresponding to 3.17% of the starting mass of HDPE.

FIG. 46 shows the GC-MS of hydrogenolysis oil products (7.18% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using mSiO₂/Pt/SiO₂ (0.06Pt wt/silica wt %) as catalyst, conditions: 0.0013 Pt wt/HDPE wt % inthe reactor for 24 h at 250° C. under H₂ (200 psi), cooled and vented atroom temperature, product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 47 shows the carbon number distribution (mass weighted) for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) usingmSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %) as catalyst, conditions: 0.0013Pt wt/HDPE wt % in the reactor 24 h at 250° C. under H₂ (200 psi).

FIG. 48 shows the SimDist GC-FID, as a second method for analyticalseparation of hydrogenolysis oil products that highlights C₁₆-centeredselectivity, from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) usingmSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %) as catalyst, conditions: 0.0013Pt wt/HDPE wt % in the reactor for 24 h at 250° C. and H₂ (200 psi),with the product isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 49 shows the ¹H NMR spectrum of oils obtained by hydrogenolysisusing mSiO₂/Pt/SiO₂. (0.06 Pt wt/silica wt %) as catalyst, conditions:0.0013 Pt wt/HDPE wt % in the reactor for 24 h at 250° C. under H₂ (200psi), the product was isolated by extraction of the solid reactionmixture with methylene chloride at 80° C. Branching is 9.7 branches per100 C, calculated by the formula (integral of CH₃/3)/{(Integral ofCH+Integral of CH₂+Integral of CH₃)/2}×100.

FIG. 50 shows the DEPT-135 NMR spectrum of oils obtained byhydrogenolysis using mSiO₂/Pt/SiO₂. (0.06 Pt wt/silica wt %) ascatalyst, conditions: 0.0013 Pt wt/HDPE wt % in the reactor for 24 h at250° C. under H₂ (200 psi), the product was isolated by extraction ofthe solid reaction mixture with methylene chloride at 80° C.

FIG. 51 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂(1.7 Pt wt/silica wt %) as catalyst, conditions: 0.0013 Pt wt/HDPE wt %in the reactor for 24 h at 250° C. under H₂ (200 psi), yielding volatilespecies corresponding to 4.37% of the starting HDPE.

FIG. 52 shows the GC-MS of hydrogenolysis oil products (15.9% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (1.7 Ptwt/silica wt %) as catalyst, conditions: 0.0013 Pt wt/HDPE wt % in thereactor for 24 h at 250° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 53 shows the Carbon number distribution for the hydrogenolysisreaction of HDPE using Pt/SiO₂ (1.7 Pt wt/silica wt %) as catalyst,conditions: 0.0013 Pt wt/HDPE wt % in the reactor for 24 h at 250° C.under H₂ (200 psi).

FIG. 54 shows the SimDist GC-FID, as a second method for analyticalseparation of hydrogenolysis oil products that highlights the broaddistribution of hydrogenolysis oil products (15.9% yield) from reactionof HDPE using Pt/SiO₂ (1.7 Pt wt/silica wt %) as catalyst, conditions:0.0013 Pt wt/HDPE wt % in the reactor for 24 h at 250° C. under H₂ (200psi), the product was isolated by extraction of the solid reactionmixture with methylene chloride at 80° C.

FIG. 55 shows the comparison of distributions of carbon numbers forhydrogenolysis reactions using the two catalysts, mSiO₂/Pt/SiO₂ andPt/SiO₂ at 0.00013 Pt wt/HDPE wt % for 24 h at 250° C. under H₂ (200psi).

FIG. 56 shows the ¹H NMR spectrum of oils obtained by hydrogenolysisusing Pt/SiO₂ (1.7 Pt wt/silica wt %) as catalyst, conditions: 0.0013 Ptwt/HDPE wt % in the reactor for 24 h at 250° C. under H₂ (200 psi), theproduct was isolated by extraction of the solid reaction mixture withmethylene chloride at 80° C.

FIG. 57 shows the DEPT-135 NMR spectrum of oils obtained byhydrogenolysis using Pt/SiO₂ (1.7 Pt wt/silica wt %) as catalyst,conditions: 0.0013 Pt wt/HDPE wt % in the reactor for 24 h at 250° C.under H₂ (200 psi), the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 58 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of polyethylene (M_(n)=15.4 kDa, Ð=1.1) usingmSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %; 2.4 nm diameter mesopores) ascatalyst, conditions: 0.0021 Pt wt/polyethylene wt % in the reactor for24 h at 250° C. under H₂ (200 psi), yielding volatile speciescorresponding to 2.4% of the starting polyethylene.

FIG. 59 shows the GC-MS of hydrogenolysis oil products (16.1% yield)from reaction of low dispersity polyethylene (M_(n)=15.4 kDa, Ð=1.1)using mSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %, 2.4 nm diameter mesopores)as catalyst, conditions: 0.0021 Pt wt/polyethylene wt % in the reactorfor 24 h at 250° C. under H₂ (200 psi), isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 60 shows the Carbon number distribution (mass weighted) for thehydrogenolysis reaction of low dispersity polyethylene (15.4 kDa, Ð=1.1)using mSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %, 2.4 nm diameter mesopores)as catalyst, conditions: 0.0021 Pt wt/polyethylene wt % in the reactor24 h at 250° C. under H₂ (200 psi).

FIG. 61 shows the C-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) usingmSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %) as catalyst, conditions: 0.00087Pt wt/HDPE wt % in the reactor for 24 h at 250° C. under H₂ (200 psi),cooled to room temperature and vented, give a yield of volatile speciescorresponding to 5.2% of the starting mass of HDPE.

FIG. 62 shows the GC-MS of hydrogenolysis oil products (12.8% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using mSiO₂/Pt/SiO₂ (0.04Pt wt/silica wt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt % inthe reactor for 24 h at 250° C. under H₂ (200 psi), cooled and vented atroom temperature, product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 63 shows the carbon number distribution (mass weighted) for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) usingmSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %) as catalyst, conditions: 0.00087Pt wt/HDPE wt % in the reactor 24 h at 250° C. under H₂ (200 psi).

FIG. 64 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂(0.59 Pt wt/silica wt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt% in the reactor for 24 h at 250° C. under H₂ (200 psi), yieldingvolatile species corresponding to 9.0% of the starting HDPE.

FIG. 65 shows the GC-MS of hydrogenolysis oil products (16.2% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (0.59 Ptwt/silica wt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt % in thereactor for 24 h at 250° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 66 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (0.59 Pt wt/silicawt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactorfor 24 h at 250° C. under H₂ (200 psi).

FIG. 67 shows a comparison of distributions of carbon numbers forhydrogenolysis reactions using the two catalysts, mSiO₂/Pt/SiO₂ andPt/SiO₂ at 0.00087 Pt wt/HDPE wt % for 24 h at 250° C. under H₂ (200psi), obtained from yield-weighted contributions of headspace andisolated oil.

FIG. 68 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/MCM-41(0.9 Pt wt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/HDPE wt %in the reactor for 24 h at 250° C. under H₂ (200 psi), yielding volatilespecies corresponding to 2.7% of the starting HDPE.

FIG. 69 shows the GC-MS of hydrogenolysis oil products (13.9% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/MCM-41 (0.9 Ptwt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/HDPE wt % in thereactor for 24 h at 250° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 70 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/MCM-41 (0.9 Ptwt/silica wt %) as as catalyst, conditions: 0.0008 Pt wt/HDPE wt % inthe reactor for 24 h at 250° C. under H₂ (200 psi).

FIG. 71 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SBA-15(0.8 Pt wt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/HDPE wt %in the reactor for 24 h at 250° C. under H₂ (200 psi), yielding volatilespecies corresponding to 1.2% of the starting HDPE.

FIG. 72 shows the GC-MS of hydrogenolysis oil products (6.4% yield) fromreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SBA-15 (0.8 Ptwt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/HDPE wt % in thereactor for 24 h at 250° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 73 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SBA-15 (0.8 Ptwt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/HDPE wt % in thereactor for 24 h at 250° C. under H₂ (200 psi).

FIG. 74 shows the GC-MS chromatogram of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using NiMo/Al₂O₃(98.8 mg) as catalyst, conditions: 24 h at 250° C. under H₂ (200 psi),yielding volatile species corresponding to 1.9% of the starting HDPE.

FIG. 75 shows the GC-MS of hydrogenolysis oil products (11.8% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using NiMo/Al₂O₃ (98.8 mg)as catalyst, conditions: 24 h at 250° C. under H₂ (200 psi), isolated byextraction of the solid reaction mixture with methylene chloride at 80°C.

FIG. 76 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using NiMo/Al₂O₃ (98.8 mg) ascatalyst, conditions: 24 h at 250° C. under H₂ (200 psi).

FIG. 77 shows the GC-MS of oil-phase products (2.5% yield) from thermalPt-free reaction of HDPE using mSiO₂/SiO₂, conditions: 0.065 gmSiO₂/SiO₂ in the reactor for 24 h at 250° C. under H₂ (200 psi).Product was isolated by extraction of the solid reaction mixture withmethylene chloride at 80° C.

FIG. 78 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE using mSiO₂/Pt/SiO₂ (0.040 Pt wt/silicawt %) as catalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactorfor 48 h at 250° C. under H₂ (200 psi), cooled to room temperature andvented, giving a yield of volatile species corresponding to 3.9% of thestarting mass of HDPE.

FIG. 79 shows the GC-MS of hydrogenolysis oil products (18.0% yield)from reaction of HDPE using mSiO₂/Pt/SiO₂ (0.040 Pt wt/silica wt %) ascatalyst, conditions: 0.00087 Pt wt/HDPE wt % in the reactor for 48 h at250° C. under H₂ (200 psi), cooled to room temperature and vented.Products were isolated by extraction of the solid reaction mixture withmethylene chloride at 80° C.

FIG. 80 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using mSiO₂/Pt/SiO₂ (0.040 Ptwt/silica wt %) as catalyst. 0.00087 Pt wt/HDPE wt % in the reactor for48 h at 250° C. under H₂ (200 psi), cooled to room temperature andvented.

FIG. 81 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂(0.59 Pt wt/silica wt %) as catalyst, conditions: 0.0018 Pt wt/HDPE wt %in the reactor for 48 h at 250° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 10.7% of the starting mass of HDPE.

FIG. 82 shows the GC-MS of hydrogenolysis oil products (33.1% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (0.59 Ptwt/silica wt %) as catalyst, conditions: 0.0018 Pt wt/HDPE wt % in thereactor for 48 h at 250° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 83 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (0.59 Pt wt/silicawt %) as catalyst, conditions: 0.0018 Pt wt/HDPE wt % in the reactor for48 h at 250° C. and H₂ (200 psi).

FIG. 84 shows the plot comparing carbon number distributions produced byhydrogenolysis reactions of HDPE using mSiO₂/Pt/SiO₂ and Pt/SiO₂ after48 h at 250° C. under H₂ (200 psi) obtained from GC-MS analysis ofheadspace gases and extracted oils, weighted based on their isolatedyields.

FIG. 85 shows the GC-MS of hydrogenolysis oil products (56.6% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using mSiO₂/Pt/SiO₂ (0.59Pt wt/silica wt %) as catalyst, conditions: 0.0039 Pt wt/HDPE wt % inthe reactor for 136 h at 250° C. under H₂ (200 psi), isolated byextraction of the solid reaction mixture with methylene chloride at 80°C.

FIG. 86 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 1.7 nmdiameter pore mSiO₂/Pt/SiO₂ (0.35 Pt wt/silica wt %) as catalyst,conditions: 0.004 Pt wt/HDPE wt % in the reactor for 24 h at 300° C.under H₂ (200 psi), cooled to room temperature and vented, giving ayield of volatile species corresponding to 33.9% of the starting mass ofHDPE.

FIG. 87 shows the GC-MS of hydrogenolysis oil products (49.8% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 2.4 nm diameter poremSiO₂/Pt/SiO₂ (0.35 Pt wt/silica wt %) as catalyst, conditions: 0.004 Ptwt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi),isolated by extraction of the solid reaction mixture with methylenechloride at 80° C.

FIG. 88 shows the Carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 1.7 nm diameter poremSiO₂/Pt/SiO₂ (0.35 Pt wt/silica wt %) as catalyst, conditions: 0.004 Ptwt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi).

FIG. 89 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 2.4 nmdiameter pore mSiO₂/Pt/SiO₂ (0.027 Pt wt/silica wt %) as catalyst,conditions: 0.004 Pt wt/HDPE wt % in the reactor for 24 h at 300° C.under H₂ (200 psi), cooled to room temperature and vented, giving ayield of volatile species corresponding to 24.2% of the starting mass ofHDPE.

FIG. 90 shows the GC-MS of hydrogenolysis oil products (73.7% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 2.4 nm diameter poremSiO₂/Pt/SiO₂ (0.027 Pt wt/silica wt %) as catalyst, conditions: 0.004Pt wt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi),isolated by extraction of the solid reaction mixture with methylenechloride at 80° C.

FIG. 91 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 2.4 nm diameter poremSiO₂/Pt/SiO₂ (0.027 Pt wt/silica wt %) as catalyst, conditions: 0.004Pt wt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi).

FIG. 92 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 3.5 nmdiameter pore mSiO₂/Pt/SiO₂ (0.033 Pt wt/silica wt %) as catalyst,conditions: 0.004 Pt wt/HDPE wt % in the reactor for 24 h at 300° C.under H₂ (200 psi), cooled to room temperature and vented, giving ayield of volatile species corresponding to 21.5% of the starting mass ofHDPE.

FIG. 93 shows the GC-MS of hydrogenolysis oil products (76.6% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 3.5 nm diameter poremSiO₂/Pt/SiO₂ (0.033 Pt wt/silica wt %) as catalyst, conditions: 0.004Pt wt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi),isolated by extraction of the solid reaction mixture with methylenechloride at 80° C.

FIG. 94 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using 3.5 nm diameter poremSiO₂/Pt/SiO₂ (0.033 Pt wt/silica wt %) as catalyst, conditions: 0.004Pt wt/HDPE wt % in the reactor for 24 h at 300° C. under H₂ (200 psi).

FIG. 95 shows the stacked GC traces comparing oil products frommSiO₂/Pt/SiO₂-catalyzed hydrogenolysis of HDPE using 1.7, 2.4, and 3.5nm diameter mesopores.

FIG. 96 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂(2.8 Pt wt/silica wt %) as catalyst, conditions: 0.004 Pt wt/HDPE wt %in the reactor for 24 h at 300° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 14.8% of the starting mass of HDPE.

FIG. 97 shows the GC-MS of hydrogenolysis oil products (23.8% yield)from reaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (2.8 Ptwt/silica wt %) as catalyst, conditions: 0.004 Pt wt/HDPE wt % in thereactor for 24 h at 300° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 98 shows the carbon number distribution for the hydrogenolysisreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) using Pt/SiO₂ (2.8 Pt wt/silicawt %) as catalyst, conditions: 0.004 Pt wt/HDPE wt % in the reactor for24 h at 300° C. under H₂ (200 psi).

FIG. 99 shows the GC-MS trace of the sampled headspace for the thermalreaction of HDPE (M_(n)=5.9 kDa, Ð=4.5) in the presence of 2.4 nmdiameter pore mSiO₂/SiO₂ material, conditions: 24 h at 300° C. under H₂(200 psi), cooled to room temperature and vented, giving a yield ofvolatile species corresponding to 0.64% of the starting mass of HDPE.

FIG. 100 shows the GC-MS of oil products (7.72% yield) from reaction ofHDPE (M_(n)=5.9 kDa, Ð=4.5) in the presence of 2.4 nm diameter poremSiO₂/SiO₂, conditions: 24 h at 300° C. under H₂ (200 psi), isolated byextraction of the solid reaction mixture with methylene chloride at 80°C.

FIG. 101 shows the carbon number distribution for the thermal reactionof HDPE (M_(n)=5.9 kDa, Ð=4.5) in the presence of 2.4 nm diameter poremSiO₂/SiO₂ (Pt-free) material, conditions: 24 h at 300° C. under H₂ (200psi).

FIG. 102 shows the GC-MS trace of the sampled headspace for the thermalreaction of 50 g of HDPE (M_(n)=5.9 kDa, Ð=4.5) in the presence of 2.4nm diameter pore mSiO₂/Pt/SiO₂ (0.27 Pt wt/silica wt %) material,conditions: 112 h at 300° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 67.9% of the starting mass of HDPE.

FIG. 103 shows the GC-MS of oil products (32.1% yield) from reaction of50 g of HDPE (M_(n)=5.9 kDa, Ð=4.5) in the presence of 2.4 nm diameterpore mSiO₂/Pt/SiO₂ (0.27 Pt wt/silica wt %), conditions: 112 h at 300°C. under H₂ (200 psi), isolated by extraction of the solid reactionmixture with methylene chloride at 80° C.

FIG. 104 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of post-consumer HDPE (M_(n)=10.6 kDa,M_(w)=150.1 kDa, Ð=14.1) using 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.04Pt wt/silica wt %) as catalyst, conditions: 0.0021 Pt wt/HDPE wt % inthe reactor for 48 h at 250° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 17.9% of the starting mass of HDPE.

FIG. 105 shows the GC-MS of hydrogenolysis oil products (20.3% yield)from reaction of post-consumer HDPE (M_(n)=10.6 kDa, M_(w)=150.1 kDa,Ð=14.1) using 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt%) as catalyst, conditions: 0.0021 Pt wt/HDPE wt % in the reactor for 48h at 250° C. under H₂ (200 psi), isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 106 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of post-consumer HDPE (M_(n)=10.6 kDa,M_(w)=150.1 kDa, Ð=14.1) using 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.04Pt wt/silica wt %) as catalyst, conditions: 0.0072 Pt wt/HDPE wt % inthe reactor for 48 h at 250° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 10.6% of the starting mass of HDPE.

FIG. 107 shows the GC-MS of hydrogenolysis oil products (33.4% yield)from reaction of post-consumer HDPE (M_(n)=10.6 kDa, M_(w)=150.1 kDa,Ð=14.1) using 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt%) as catalyst, conditions: 0.0072 Pt wt/HDPE wt % in the reactor for 24h at 300° C. under H₂ (200 psi), isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 108 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of iPP using 2.4 nm diameter pore mSiO₂/Pt/SiO₂(0.04 Pt wt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/iPP wt %in the reactor for 24 h at 300° C. under H₂ (200 psi), cooled to roomtemperature and vented, giving a yield of volatile species correspondingto 21.0% of the starting mass of iPP.

FIG. 109 shows the GC-MS of hydrogenolysis oil products (78.9% yield)from reaction of iPP using 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.04 Ptwt/silica wt %) as catalyst, conditions: 0.0008 Pt wt/iPP wt % in thereactor for 24 h at 300° C. under H₂ (200 psi), isolated by extractionof the solid reaction mixture with methylene chloride at 80° C.

FIG. 110 shows the GC-MS trace of the sampled headspace for thehydrogenolysis reaction of iPP using Pt/SiO₂ (2.3 Pt wt/silica wt %) ascatalyst, conditions: 0.0008 Pt wt/iPP wt % in the reactor for 24 h at300° C. under H₂ (200 psi), cooled to room temperature and vented,giving a yield of volatile species corresponding to 47.2% of thestarting mass of iPP.

FIG. 111 shows the GC-MS of hydrogenolysis oil products (52.8% yield)from reaction of iPP using Pt/SiO₂ (2.3 Pt wt/silica wt %) as catalyst,conditions: 0.0008 Pt wt/iPP wt % in the reactor for 24 h at 300° C.under H₂ (200 psi), isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 112 shows the ¹³C CPMAS (a) and CP-refocused-INADEQUATE (b) spectraof ¹³C-enriched polyethylene adsorbed on mSiO₂.

FIG. 113 shows the normalized ¹³C Bloch decay MAS spectra of the¹³C-enriched polyethylene that was adsorbed onto the as-synthesized(black) and partly dehydroxylated (dashed) mSiO₂ material.

FIGS. 114 A-B shows the ¹³C CPMAS (a) and Bloch decay MAS (b) NMRspectra of the 130 kg/mol ¹³C-enriched polyethylene adsorbed ontodifferent silica materials.

FIG. 115 shows the ¹³C Bloch decay MAS NMR spectrum of natural abundanceeicosane loaded into the 1.5 nm mSiO₂ material at a temperature of 45°C. The three smaller peaks originate from the chain ends and are notdetectable in the case of polyethylene.

FIG. 116 shows the ¹³C 2D EXSY spectra taken for the mSiO₂/SiO₂ samplewith mixing times of 0 and 1 s. F1 slices are shown on the right wherethe appearance of the exchange peak is evident.

FIGS. 117 A-C shows the Summed F1 projections of selected ¹³C EXSY NMRspectra of the 130 kg/mol ¹³C-enriched polyethylene adsorbed onto mSiO₂.From top to bottom, the spectra correspond to mixing times of 2 s, 0.25s, and 0 s. From left to right, the spectra were collected at differenttemperatures, with a) 72° C., b) 93° C., and c) 114° C. The 2 s mixingtime spectra have examples of the fits used to extract the relativeintensities of the peaks. All spectra are presented with identicalvertical intensities and horizontal scaling.

FIG. 118 shows the Arrhenius plot used to determine the activationenergy for the intra-pore diffusion at different mixing time(t_(mix)=0.125, 0.25, 1, 2, and 4 s). The simultaneous fit of all fivemixing times to a single activation energy is depicted with the solidlines, while the dotted lines correspond to the fit from a single mixingtime alone.

FIG. 119 shows the pathways for catalyst-controlled hydrogenolysis ofpolyethylene (PE) into wax-like oligomers or gases.

FIGS. 120 A-F shows the TEM images for Pt-1.7/SiO₂ (a), Pt-2.9/SiO₂ (c),Pt-5.0/SiO₂ (e), mSiO₂/Pt-1.7/SiO₂ (b), mSiO₂/Pt-2.9/SiO₂ (d), andmSiO₂/Pt-5.0/SiO₂ (f) with dark field images of the cores ofmSiO₂/Pt-x/SiO₂ are shown as insets in (b, d, f) at equivalentmagnification.

FIG. 121 shows the bar chart showing time-dependent mass-based fractionsof gas phase and methylene chloride-extracted waxes, and residual solidproducts after mSiO₂/Pt-1.7/SiO₂-catalyzed hydrogenolysis of PE(M_(n)=20 kDa) at 300° C. under 0.89 MPa H₂. The mass fraction ofextractable species increases from 6 to 15 h, while only a smallincrease in low molecular weight gas phase products is observed overthat time. Quantitative conversion of solids (20 h) is accompanied bysubstantial increase in gas products (over-hydrogenolysis).

FIG. 122 shows the similar carbon number distributions of extractedwaxes with similarly high conversions (˜80%). Top: 86% conversion ofsolid polymer and 73.6% yield of extracted oils from mSiO₂/Pt-1.7/SiO₂,15 h at 300° C.; Center: 85.8% conversion of solid polymer and 70.8%yield of extracted oils from mSiO₂/Pt-2.9/SiO₂, 20 h at 300° C.; Bottom:73.8% conversion of solid polymer and 61.7% yield of extracted oils frommSiO₂/Pt-5.0/SiO₂, 20 h at 300° C.

FIG. 123 shows the carbon number distribution of extracted waxes(weighted by % yield of extracted waxes) from hydrogenolysis of PE usingmSiO₂/Pt-1.7/SiO₂ (0.085 wt/silica wt. %) as catalyst. Conditions:0.0007 Pt wt/PE wt. % in the reactor for 8-15 h at 300° C. under H₂ (at0.89 MPa), and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C. from the reactor thatwas vented at 25° C.

FIG. 124 shows the similar carbon number distributions of extractedwaxes with similarly low conversions (˜25%). Top: 24.8% conversion ofsolid polymer and 18.7% yield of extracted oils from mSiO₂/Pt-1.7/SiO₂,6 h at 300° C.; Center: 28.7% conversion of solid polymer and 20.4%yield of extracted oils from mSiO₂/Pt-2.9/SiO₂, 8 h at 300° C.; Bottom:26.2% conversion of solid polymer and 17.5% yield of extracted oils frommSiO₂/Pt-5.0/SiO₂, 12 h at 300° C.

FIGS. 125 A-C shows the TEM images and size distribution histogram(inset) for 1.7 (±0.3) nm Pt NPs (a), 2.9 (±0.5) nm Pt NPs (b), and 5.0(±1.0) nm Pt NPs (c) with distributions having been based on 150particle counts.

FIG. 126 shows the N₂ sorption isotherms of the mSiO₂/Pt—X/SiO₂catalysts.

FIG. 127 shows the pore size distributions of the mSiO₂/Pt—X/SiO₂catalysts from BJH model, with adsorption branch.

FIGS. 128 A-B shows the dark-field TEM images of post-reaction andpost-DCM extraction catalyst: Pt-1.7/SiO₂ (a), and mSiO₂/Pt-1.7-SiO₂(b). Inset figure in (b) is a higher magnitude image with bettercontrast to show the Pt dispersion.

FIG. 129 shows the bar chart showing mass-based fractions of products(gases, methylene chloride-extracted waxes, and the residual solid)after mSiO₂/Pt—X/SiO₂-catalyzed hydrogenolysis of PE (M_(n)=20 kDa,M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. for 6 h under H₂ (0.89 MPa). ThePE conversions into liquid and gaseous species were 25%, 15% and 6% inexperiments employing 1.7 nm, 2.9 nm, and 5.0 nm Pt NPs as the catalyst,respectively.

FIG. 130 shows the bar chart showing mass-based fractions of products(gases, methylene chloride-extracted waxes, and the residual solid)after mSiO₂/Pt—X/SiO₂-catalyzed hydrogenolysis of PE (M_(n)=20 kDa,M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. for 8 h under H₂ (0.89 MPa). ThePE conversions into liquid and gaseous species were 40%, 28% and 15% inexperiments employing 1.7 nm, 2.9 nm, and 5.0 nm Pt NPs as the catalyst,respectively.

FIG. 131 shows the bar chart showing mass-based fractions of products(gases, methylene chloride-extracted waxes, and the residual solid)after mSiO₂/Pt—X/SiO₂-catalyzed hydrogenolysis of PE (M_(n)=20 kDa,M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. for 12 h under H₂ (0.89 MPa). ThePE conversions into liquid and gaseous species were 62%, 56% and 26% inexperiments employing 1.7 nm, 2.9 nm, and 5.0 nm Pt NPs as the catalyst,respectively.

FIG. 132 shows the bar chart showing mass-based fractions of products(gases, methylene chloride-extracted waxes, and the residual solid)after mSiO₂/Pt—X/SiO₂-catalyzed hydrogenolysis of PE (M_(n)=20 kDa,M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. for 20 h under H₂ (0.89 MPa). ThePE conversions into liquid and gaseous species were 100%, 86% and 74% inexperiments employing 1.7 nm, 2.9 nm, and 5.0 nm Pt NPs as the catalyst,respectively.

FIG. 133 shows the bar chart showing time-dependence of the mass-basedfractions of products (gases, methylene chloride-extracted waxes, andthe residual solid) after mSiO₂/Pt-2.9/SiO₂-catalyzed hydrogenolysis ofPE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. under H₂ (0.89MPa). The mass fraction of species that extract into methylene chlorideat 80° C. increases from catalytic experiments performed for 6 h tothose performed for 20 h, while only a small increase the mass fractionof low molecular weight gas phase products is observed over that time.

FIG. 134 shows the bar chart showing time-dependence of the mass-basedfractions of products (gases, methylene chloride-extracted waxes, andthe residual solid) after mSiO₂/Pt-5.0/SiO₂-catalyzed hydrogenolysis ofPE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) at 300° C. under H₂ (0.89MPa). The mass fraction of species that extract into methylene chlorideat 80° C. increases from catalytic experiments performed for 6 h tothose performed for 20 h, while only a small increase the mass fractionof low molecular weight gas phase products is observed over that time.

FIG. 135 shows the GC-FID trace of the sampled headspace (correspondingto 9.1% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085Pt wt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 6 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 136 shows the GC-MS of extracted waxes (18.7% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 6 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 137 shows the carbon number distribution of extracted waxes (18.7%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 Pt wt/PE wt % was heated in the reactor for 6 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 138 shows the GC-FID trace of the sampled headspace (correspondingto 8.4% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40Pt wt/silica wt %) as catalyst. Conditions: 0.0019 wt/PE wt % was heatedfor 6 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 139 shows the GC-MS of extracted waxes (6.4% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-2.9/SiO₂ (0.40 wt/silica wt %) as catalyst. Conditions: 0.0019Pt wt/PE wt % was heated in the reactor for 6 h at 300° C. under H₂ (at0.89 MPa), the reactor was cooled to 25° C., the pressure was released,and the product was isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 140 shows the carbon number distribution for the oil products (6.4%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40 wt/silica wt %) as catalyst.Conditions: 0.0019 Pt wt/PE wt % was heated in the reactor for 6 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 141 shows the GC-FID trace of the sampled headspace (correspondingto 3.9% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28Pt wt/silica wt %) as catalyst. Conditions: 0.0034 wt/PE wt % was heatedfor 6 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 142 shows the GC-MS of extracted waxes (1.9% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst. Conditions:0.0034 Pt wt/PE wt % was heated in the reactor for 6 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 143 shows the carbon number distribution of extracted waxes (1.9%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28 wt/silica wt %) as catalyst.Conditions: 0.0034 Pt wt/PE wt % was heated in the reactor for 6 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 144 shows the GC-FID trace of the sampled headspace (correspondingto 11.6% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085Pt wt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 8 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 145 shows the GC-MS of extracted waxes (29.0% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 8 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 146 shows the carbon number distribution of extracted waxes (29.0%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 Pt wt/PE wt % was heated in the reactor for 8 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 147 shows the GC-FID trace of the sampled headspace (correspondingto 8.3% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40Pt wt/silica wt %) as catalyst. Conditions: 0.0019 wt/PE wt % was heatedfor 8 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 148 shows the GC-MS of extracted waxes (20.4% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst. Conditions:0.0019 Pt wt/PE wt % was heated in the reactor for 8 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 149 shows the carbon number distribution of extracted waxes (20.4%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst.Conditions: 0.0019 Pt wt/PE wt % was heated in the reactor for 8 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 150 shows the GC-FID trace of the sampled headspace (correspondingto 4.7% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28Pt wt/silica wt %) as catalyst. Conditions: 0.0034 wt/PE wt % was heatedfor 8 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 151 shows the GC-MS of extracted waxes (8.5% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst. Conditions:0.0034 Pt wt/PE wt % was heated in the reactor for 8 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 152 shows the Carbon number distribution of extracted waxes (8.5%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst.Conditions: 0.0034 Pt wt/PE wt % was heated in the reactor for 8 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 153 shows the GC-FID trace of the sampled headspace (correspondingto 2.4% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/SiO₂ as catalyst.Conditions: 35 mg of mSiO₂/SiO₂ (0 Pt wt/PE wt %) was heated for 12 h at300° C. under H₂ (at 0.89 MPa) in the reactor, which was then cooled,vented and sampled at 25° C.

FIG. 154 shows the GC-MS of extracted waxes (1.2% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/SiO₂ as catalyst. Conditions: 35 mg of mSiO₂/SiO₂ (0 Pt wt/PE wt%) was heated in the reactor for 12 h at 300° C. under H₂ (at 0.89 MPa),the reactor was cooled to 25° C., the pressure was released, and theproduct was isolated by extraction of the solid reaction mixture withmethylene chloride at 80° C.

FIG. 155 shows the carbon number distribution (1.2% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/SiO₂ as catalyst. Conditions: 35 mg of mSiO₂/SiO₂ (0 Pt wt/PE wt%) was heated in the reactor for 12 h at 300° C. under H₂ (at 0.89 MPa),the reactor was cooled to 25° C., the pressure was released, and theproduct was isolated by extraction of the solid reaction mixture withmethylene chloride at 80°.

FIG. 156 shows the GC-FID trace of the sampled headspace (correspondingto 11.4% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085Pt wt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 157 shows the GC-MS of extracted waxes (50.5% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 12 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 158 shows the carbon number distribution of extracted waxes (50.5%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 159 shows the GC-FID trace of the sampled headspace (correspondingto 12.0% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40Pt wt/silica wt %) as catalyst. Conditions: 0.0019 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 160 shows the GC-MS of extracted waxes (43.8% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst. Conditions:0.0019 Pt wt/PE wt % was heated in the reactor for 12 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 161 shows the carbon number distribution of extracted waxes (43.8%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst.Conditions: 0.0019 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 162 shows the GC-FID trace of the sampled headspace (correspondingto 9.8% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28Pt wt/silica wt %) as catalyst. Conditions: 0.0034 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 163 shows the GC-MS of extracted waxes (17.5% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst. Conditions:0.0034 Pt wt/PE wt % was heated in the reactor for 12 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 164 shows the carbon number distribution of extracted waxes (17.5%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst.Conditions: 0.0034 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 165 shows the GC-FID trace of the sampled headspace (correspondingto 12.4% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085Pt wt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 15 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 166 shows the GC-MS of extracted waxes (73.6% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 15 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 167 shows the carbon number distribution of extracted waxes (73.6%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 Pt wt/PE wt % was heated in the reactor for 15 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 168 shows the GC-FID trace of the sampled headspace (correspondingto 66.3% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-1.7/SiO₂ (0.085Pt wt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 20 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 169 shows the GC-MS of extracted waxes (33.7% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % heated in the reactor for 20 h at 300° C. under H₂(at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 170 shows the carbon number distribution of extracted waxes(corresponding to 33.7% of the starting PE) for the hydrogenolysisreaction of PE (M_(n)=20 kDa, M_(w)=90 kDa, p=0.92 g/mL) usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 15 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 171 shows the GC-FID trace of the sampled headspace (correspondingto 14.9% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40Pt wt/silica wt %) as catalyst. Conditions: 0.0019 wt/PE wt % heated for20 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which was thencooled, vented and sampled at 25° C.

FIG. 172 shows the GC-MS of extracted waxes (70.8% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst. Conditions:0.0019 Pt wt/PE wt % was heated in the reactor for 20 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 173 shows the carbon number distribution of extracted waxes (70.8%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-2.9/SiO₂ (0.40 Pt wt/silica wt %) as catalyst.Conditions: 0.0019 Pt wt/PE wt % was heated in the reactor for 20 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 174 shows the GC-FID trace of the sampled headspace (correspondingto 9.8% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28Pt wt/silica wt %) as catalyst. Conditions: 0.0034 wt/PE wt % was heatedfor 20 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 175 shows the GC-MS of extracted waxes (61.7% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingmSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst. Conditions:0.0034 Pt wt/PE wt % in the reactor for 20 h at 300° C. under H₂ (at0.89 MPa), the reactor was cooled to 25° C., the pressure was released,and the product was isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 176 shows the carbon number distribution of extracted waxes (61.7%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using mSiO₂/Pt-5.0/SiO₂ (0.28 Pt wt/silica wt %) as catalyst.Conditions: 0.0034 Pt wt/PE wt % was heated in the reactor for 20 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 177 shows the GC-FID trace of the sampled headspace (correspondingto 1.8% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using Pt-1.7/SiO₂ (0.72 Ptwt/silica wt %) as catalyst. Conditions: 0.0007 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, then cooled,vented and sampled at 25° C.

FIG. 178 shows the GC-MS of extracted waxes (2.7% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingPt-1.7/SiO₂ (0.72 Pt wt/silica wt %) as catalyst. Conditions: 0007 Ptwt/PE wt % was heated in the reactor for 12 h at 300° C. under H₂ (at0.89 MPa), the reactor was cooled to 25° C., the pressure was released,and the product was isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 179 shows the carbon number distribution of extracted waxes (2.7%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using Pt-1.7/SiO₂ (0.72 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 180 shows the GC-FID trace of the sampled headspace (correspondingto 1.2% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using Pt-2.9/SiO₂ (3.98 Ptwt/silica wt %) as catalyst. Conditions: 0.0019 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen cooled, vented and sampled at 25° C.

FIG. 181 shows the GC-MS of extracted waxes (3.1% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingPt-2.9/SiO₂ (3.98 Pt wt/silica wt %) as catalyst. Conditions: 0.0019 Ptwt/PE wt % was heated in the reactor for 12 h at 300° C. under H₂ (at0.89 MPa), the reactor was cooled to 25° C., the pressure was released,and the product was isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 182 shows the carbon number distribution of extracted waxes (3.1%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using Pt-2.9/SiO₂ (3.98 Pt wt/silica wt %) as catalyst.Conditions: 0.0019 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 183 shows the GC-FID trace of the sampled headspace (correspondingto 6.4% of the starting PE) for the hydrogenolysis reaction of PE(M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) using Pt-5.0/SiO₂ (3.78 Ptwt/silica wt %) as catalyst. Conditions: 0.0034 wt/PE wt % was heatedfor 12 h at 300° C. under H₂ (at 0.89 MPa) in the reactor, which wasthen vented and sampled at 25° C.

FIG. 184 shows the GC-MS of extracted waxes (7.1% yield) fromhydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92 g/mL) usingPt-5.0/SiO₂ (3.78 Pt wt/silica wt %) as catalyst. Conditions: 0.0034 Ptwt/PE wt % was heated in the reactor for 12 h at 300° C. under H₂ (at0.89 MPa), the reactor was cooled to 25° C., the pressure was released,and the product was isolated by extraction of the solid reaction mixturewith methylene chloride at 80° C.

FIG. 185 shows the carbon number distribution of extracted waxes (7.1%yield) from hydrogenolysis of PE (M_(n)=20 kDa, M_(w)=90 kDa, ρ=0.92g/mL) using Pt-5.0/SiO₂ (3.78 Pt wt/silica wt %) as catalyst.Conditions: 0.0034 Pt wt/PE wt % was heated in the reactor for 12 h at300° C. under H₂ (at 0.89 MPa), the reactor was cooled to 25° C., thepressure was released, and the product was isolated by extraction of thesolid reaction mixture with methylene chloride at 80° C.

FIG. 186 shows the bubble wrap plastic waste obtained from backyard aslitter, no pre-cleaning was performed prior to reactions.

FIG. 187 shows the GC-FID trace of the sampled headspace (correspondingto 10.3% of the starting PE) for the hydrogenolysis reaction of bubblewrap using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst.Conditions: 0.0007 wt/PE wt % was heated for 12 h at 300° C. under H₂(at 0.89 MPa) in the reactor, which was then vented and sampled at 25°C.

FIG. 188 shows the GC-MS of extracted waxes (28.8% yield) fromhydrogenolysis of bubble wrap litter using mSiO₂/Pt-1.7/SiO₂ (0.085 Ptwt/silica wt %) as catalyst. Conditions: 0.0007 Pt wt/PE wt % in thereactor for 12 h at 300° C. under H₂ (at 0.89 MPa), the reactor wascooled to 25° C., the pressure was released, and the product wasisolated by extraction of the solid reaction mixture with methylenechloride at 80° C.

FIG. 189 shows the Carbon number distribution of extracted waxes (28.8%yield) from hydrogenolysis of backyard bubble wrap litter usingmSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt %) as catalyst. Conditions:0.0007 Pt wt/PE wt % was heated in the reactor for 12 h at 300° C. underH₂ (at 0.89 MPa), the reactor was cooled to 25° C., the pressure wasreleased, and the product was isolated by extraction of the solidreaction mixture with methylene chloride at 80° C.

FIG. 190 shows the HT-GPC analysis of molecular mass and distributionsof PE (Alfa Aesar 041321).

DETAILED DESCRIPTION

As used above, and throughout the description herein, the followingterms, unless otherwise indicated, shall be understood to have thefollowing meanings. If not defined otherwise herein, all technical andscientific terms used herein have the same meaning as is commonlyunderstood by one of ordinary skill in the art to which this technologybelongs. In the event that there is a plurality of definitions for aterm herein, those in this section prevail unless stated otherwise.

The term “block copolymer” or “block polymer” refers to a macromoleculeconsisting of long sequences of different repeat units. Exemplary blockpolymers include, but are not limited to A_(n)B_(m), A_(n)B_(m)A_(m),A_(n)B_(m)C_(k), or A_(n)B_(m)C_(k)A_(n).

The term “copolymer” refers to a polymer derived from more than onespecies of monomer.

The term “graft copolymer” refers to a type of copolymer which one ormore blocks of homopolymer are grafted as branches onto a main chaini.e. it is a branched copolymer with one or more side chains of ahomopolymer attached to the backbone of the main chain.

The term “metal nanoparticle” refers to a submicron scale entities madeof pure metals (e.g., nickel, palladium, platinum, cobalt, rhodium,iridium, iron, ruthenium, osmium, manganese, rhenium, chromium,molybdenum, and tungsten), combination of metals (e.g. PtSn), or theircompounds.

The term “number average molecular weight (M_(n))” refers to the totalweight of the polymer divided by the number of molecules in the polymer.

The term “polymeric blend” refers to a mixture in which at least twopolymers are blended together to create a new material with differentphysical properties.

The term “polyolefinic polymer” refers to a polymer produced from anolefin with the general formula C_(n)H_(2n) as a monomer.

Catalyst

One aspect of the present application relates to a catalyst whichcomprises a silica core having an outer surface and a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said silica core. Theouter surface of the mesoporous silica shell has openings leading topores within the mesoporous silica shell which extend toward the outersurface of said silica core. The catalyst also includes catalyticallyactive metal nanoparticles positioned within the pores proximate to saidcore, wherein the catalytic metal nanoparticles comprise about 0.0001 wt% to about 1.0 wt % of the catalyst.

In another embodiment of the catalyst, the catalytic metal nanoparticlecomprises about 0.085 wt % of the catalyst.

In another embodiment of the catalyst, the catalytic metal nanoparticlecomprises about 0.28 wt % of the catalyst.

In another embodiment of the catalyst, the catalytic metal nanoparticlecomprises about 0.35 wt % of the catalyst.

In another embodiment of the catalyst, the catalytic metal nanoparticlecomprises about 0.40 wt % of the catalyst.

In another embodiment of the catalyst, the silica core further comprisesa functional group selected from the group consisting of: amines,carboxylic acids, alcohols, thiols, phosphorus, and combinationsthereof.

In another embodiment of the catalyst, the catalytic metal nanoparticlesare positioned on the outer surface of the silica core.

In another embodiment of the catalyst, the catalyst has a mean particlediameter of about 100 nm to about 1000 nm.

In another embodiment of the catalyst, the catalyst has a mean particlediameter of about 240 nm.

In another embodiment of the catalyst, the silica core has a meanparticle diameter of about 50 nm to about 500 nm.

In another embodiment of the catalyst, the silica core has a meanparticle diameter of about 127 nm.

In another embodiment of the catalyst, the metal for the catalytic metalnanoparticle is selected from the group consisting of nickel, palladium,platinum, cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese,rhenium, chromium, molybdenum, tungsten, and combinations thereof.

In another embodiment of the catalyst, the catalytic metal nanoparticlehas a mean particle diameter of about 1 nm to about 10 nm.

In another embodiment of the catalyst, the catalytic metal nanoparticlehas a mean particle diameter of about 1.7 nm.

In another embodiment of the catalyst, the catalytic metal nanoparticlehas a mean particle diameter of about 2.9 nm.

In another embodiment of the catalyst, the catalytic metal nanoparticlehas a mean particle diameter of about 3.2 nm.

In another embodiment of the catalyst, the catalytic metal nanoparticlehas a mean particle diameter of about 5.0 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 50 nm to about 500 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 65 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 110 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 120 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 220 nm.

In another embodiment of the catalyst, the mesoporous silica shell has athickness of about 300 nm.

In another embodiment of the catalyst, the mesoporous silica shell has apore diameter of about 1 nm to about 10 nm.

In another embodiment of the catalyst, the mesoporous silica shell has apore diameter of about 2.4 nm.

In another embodiment of the catalyst, the pores have a length of aboutthe thickness of the mesoporous silica shell measured between its innerand outer surfaces.

Methods of Use

Another aspect of the present application relates to a process forcatalytically hydrogenolysizing a polyolefinic polymer, which comprisesproviding a polyolefinic polymer and subjecting said polyolefinicpolymer to a hydrogenolysis reaction in the presence of a catalyst tocleave the polymer into hydrocarbon segments. The catalyst comprises asilica core having an outer surface and a mesoporous silica shell havingan outer surface and an inner surface with the inner surface beinginside the outer surface of said mesoporous silica shell proximate toand surrounding the outer surface of said silica core, wherein the outersurface of the mesoporous silica shell has openings leading to poreswithin the mesoporous silica shell which extend toward the outer surfaceof said silica core. The catalyst also includes catalytic metalnanoparticles positioned within the pores proximate to said core tocleave said polyolefinic polymer entering said mesoporous silica shellthrough the openings into hydrocarbon segments.

In carrying out the process, the catalyst used has the characteristicsdescribed herein.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle comprises about0.0001 wt % to about 1.0 wt % of the catalyst.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle comprises about0.085 wt % of the catalyst.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle comprises about0.28 wt % of the catalyst.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle comprises about0.35 wt % of the catalyst.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle comprises about0.40 wt % of the catalyst.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle has a meanparticle diameter of about 1 nm to about 10 nm.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle has a meanparticle diameter of about 1.7 nm.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle has a meanparticle diameter of about 2.9 nm.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle has a meanparticle diameter of about 3.2 nm.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the catalytic metal nanoparticle has a meanparticle diameter of about 5.0 nm.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said polyolefinic polymer is selected from thegroup consisting of physical mixtures of polymers, polymeric blends,copolymers, block copolymers, graft copolymers, and combinationsthereof.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said polyolefinic polymer is selected from thegroup consisting of high density polyethylene, isostatic polypropylene,medium density polyethylene, low density polyethylene, linear lowdensity polyethylene, ultra high molecular weight polyethylene, andcombinations thereof.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said polyolefinic polymer is high densitypolyethylene having a number average molecular weight (M_(n)) of5000-100000 Da. In some embodiments of the number average molecularweight (M_(n)) is 5000-75000 Da, 10000-100000 Da, 10000-75000 Da,10000-50000 Da, or 5000-50000 Da.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said polyolefinic polymer has a longitudinalextent between opposed ends. The step of subjecting said polyolefinicpolymer to a hydrogenolysis reaction comprises extending an end of saidpolyolefinic polymer through the openings and into the pores of saidmesoporous silica shell and cleaving said polyolefinic polymer intohydrocarbon segments in the pores using the catalytic metalnanoparticle.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the pores have dimensions selected to produce asize distribution of the hydrocarbon segments as a result ofhydrogenolysis.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, the pores have a diameter selected to permit alength of said polyolefinic polymer to enter the pores which yield aparticular segment length as a result of hydrogenolysis.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a pressure ofabout 1 psi to about 1000 psi.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a pressure ofabout 10 psi to about 1000 psi, about 50 psi to about 1000 psi, about100 psi to about 1000 psi, about 150 psi to about 1000 psi, about 200psi to about 1000 psi, about 250 psi to about 1000 psi, about 300 psi toabout 1000 psi, about 400 psi to about 1000 psi, about 500 psi to about1000 psi, about 600 psi to about 1000 psi, about 700 psi to about 1000psi, about 800 psi to about 1000 psi, about 900 psi to about 1000 psi,about 1 psi to about 900 psi, about 1 psi to about 800 psi, about 1 psito about 700 psi, about 1 psi to about 600 psi, about 1 psi to about 500psi, about 1 psi to about 400 psi, about 1 psi to about 300 psi, about 1psi to about 250 psi, about 1 psi to about 200 psi, about 1 psi to about150 psi, about 1 psi to about 100 psi, about 1 psi to about 50 psi, orabout 1 psi to about 10 psi.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a pressure ofabout 200 psi.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a temperatureof about 150° C. to about 400° C.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a temperatureof about 200° C. to about 400° C., about 250° C. to about 400° C., about300° C. to about 400° C., about 350° C. to about 400° C., about 150° C.to about 350° C., about 150° C. to about 300° C., about 150° C. to about250° C., or about 150° C. to about 200° C.

In another embodiment of the process for catalytically hydrogenolysizinga polyolefinic polymer, said subjecting is carried out at a temperatureof about 250° C.

Methods of Preparing the Catalyst

The catalyst of the present application can be prepared by dispersingSiO₂ spheres in an alcoholic solvent and functionalizing them with agroup such as an amine. The functionalized SiO₂ spheres are then driedbefore being resuspended in an alcoholic solvent and then treated withPt nanoparticles suspended in an alcoholic solvent. The Pt/SiO₂ sphereswere dried before being resuspended in an alcoholic solvent and then ashell of mesoporous silica (mSiO₂) was grown on top of the Pt/SiO₂spheres, the shell having pores organized radially from the silicasphere and the pore length being equal to the thickness of the mSiO₂shell. This three-layered spherical shell-type construction(mSiO₂/Pt/SiO₂) places the Pt nanoparticles at the terminal end oflinear channels (i.e., at the bottom of wells).

A further aspect of the present application relates to a method ofpreparing a catalyst which comprises adding a functional group to asilica core having an outer surface to produce a functionalized silicacore. The functionalized silica core is contacted with a plurality ofcatalytic metal nanoparticles wherein the catalytic metal nanoparticlesadhere to the surface of the functionalized silica core to produce afunctionalized silica core supported catalytic metal nanoparticles. Thefunctionalized silica core supported catalytic metal nanoparticles isthen contacted with a silicon compound to produce a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said functionalizedsilica core supported catalytic metal nanoparticles. The outer surfaceof the mesoporous silica shell has openings leading to pores within themesoporous silica shell which extend toward the outer surface of saidfunctionalized silica core supported catalytic metal nanoparticles.

In another embodiment of the method of preparing a catalyst, thefunctional group is selected from the group consisting of: amines,carboxylic acids, alcohols, thiols, phosphorus, and combinationsthereof.

In carrying out the method of preparing a catalyst, the catalyst has thecharacteristics described above.

In another embodiment of the method of preparing a catalyst, the metalfor the plurality of catalytic metal nanoparticles is selected from thegroup consisting of nickel, palladium, platinum, cobalt, rhodium,iridium, iron, ruthenium, osmium, manganese, rhenium, chromium,molybdenum, tungsten, and combinations thereof.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.0001 wt %to about 1.0 wt % of the catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.00025 wt %to about 1.0 wt % of the catalyst, about 0.0005 wt % to about 1.0 wt %of the catalyst, about 0.00075 wt % to about 1.0 wt % of the catalyst,about 0.001 wt % to about 1.0 wt % of the catalyst, about 0.0025 wt % toabout 1.0 wt % of the catalyst, about 0.005 wt % to about 1.0 wt % ofthe catalyst, about 0.0075 wt % to about 1.0 wt % of the catalyst, about0.01 wt % to about 1.0 wt % of the catalyst, about 0.025 wt % to about1.0 wt % of the catalyst, about 0.05 wt % to about 1.0 wt % of thecatalyst, about 0.075 wt % to about 1.0 wt % of the catalyst, about 0.1wt % to about 1.0 wt % of the catalyst, about 0.2 wt % to about 1.0 wt %of the catalyst, about 0.3 wt % to about 1.0 wt % of the catalyst, about0.4 wt % to about 1.0 wt % of the catalyst, about 0.5 wt % to about 1.0wt % of the catalyst, about 0.6 wt % to about 1.0 wt % of the catalyst,about 0.7 wt % to about 1.0 wt % of the catalyst, about 0.8 wt % toabout 1.0 wt % of the catalyst, or about 0.9 wt % to about 1.0 wt % ofthe catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.085 wt % ofthe catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.28 wt % ofthe catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.35 wt % ofthe catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles comprises about 0.40 wt % ofthe catalyst.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles has a mean particle diameterof about 1 nm to about 10 nm.

In another embodiment of the method of preparing a catalyst, theplurality of catalytic metal nanoparticles has a mean particle diameterof about 2 nm to about 10 nm, about 3 nm to about 10 nm, about 4 nm toabout 10 nm, about 5 nm to about 10 nm, about 6 nm to about 10 nm, about7 nm to about 10 nm, about 8 nm to about 10 nm, about 9 nm to about 10nm, about 1 nm to about 9 nm, about 1 nm to about 8 nm, about 1 nm toabout 7 nm, about 1 nm to about 6 nm, about 1 nm to about 5 nm, about 1nm to about 4 nm, about 1 nm to about 3 nm, or about 1 nm to about 2 nm.

In another embodiment of the method of preparing a catalyst, thecatalytic metal nanoparticle has a mean particle diameter of about 1.7nm.

In another embodiment of the method of preparing a catalyst, thecatalytic metal nanoparticle has a mean particle diameter of about 2.9nm.

In another embodiment of the method of preparing a catalyst, thecatalytic metal nanoparticle has a mean particle diameter of about 3.2nm.

In another embodiment of the method of preparing a catalyst, thecatalytic metal nanoparticle has a mean particle diameter of about 5.0nm.

In another embodiment of the method of preparing a catalyst, the siliconcompound is selected from the group consisting of: orthosilicates,metasilicates, pyrosilicates, and combinations thereof.

According to any embodiment of the present application, the catalyticmetal nanoparticle comprises about 0.00025 wt % to about 1.0 wt % of thecatalyst, about 0.0005 wt % to about 1.0 wt % of the catalyst, about0.00075 wt % to about 1.0 wt % of the catalyst, about 0.001 wt % toabout 1.0 wt % of the catalyst, about 0.0025 wt % to about 1.0 wt % ofthe catalyst, about 0.005 wt % to about 1.0 wt % of the catalyst, about0.0075 wt % to about 1.0 wt % of the catalyst, about 0.01 wt % to about1.0 wt % of the catalyst, about 0.025 wt % to about 1.0 wt % of thecatalyst, about 0.05 wt % to about 1.0 wt % of the catalyst, about 0.075wt % to about 1.0 wt % of the catalyst, about 0.1 wt % to about 1.0 wt %of the catalyst, about 0.2 wt % to about 1.0 wt % of the catalyst, about0.3 wt % to about 1.0 wt % of the catalyst, about 0.4 wt % to about 1.0wt % of the catalyst, about 0.5 wt % to about 1.0 wt % of the catalyst,about 0.6 wt % to about 1.0 wt % of the catalyst, about 0.7 wt % toabout 1.0 wt % of the catalyst, about 0.8 wt % to about 1.0 wt % of thecatalyst, or about 0.9 wt % to about 1.0 wt % of the catalyst.

According to any embodiment of the present application, the catalyst hasa mean particle diameter of about 110 nm to about 1000 nm, about 120 nmto about 1000 nm, about 130 nm to about 1000 nm, about 140 nm to about1000 nm, about 150 nm to about 1000 nm, about 160 nm to about 1000 nm,about 170 nm to about 1000 nm, about 180 nm to about 1000 nm, about 190nm to about 1000 nm, about 200 nm to about 1000 nm, about 210 nm toabout 1000 nm, about 220 nm to about 1000 nm, about 230 nm to about 1000nm, about 240 nm to about 1000 nm, about 250 nm to about 1000 nm, about260 nm to about 1000 nm, about 270 nm to about 1000 nm, about 280 nm toabout 1000 nm, about 290 nm to about 1000 nm, about 300 nm to about 1000nm, about 310 nm to about 1000 nm, about 320 nm to about 1000 nm, about330 nm to about 1000 nm, about 340 nm to about 1000 nm, about 350 nm toabout 1000 nm, about 360 nm to about 1000 nm, about 370 nm to about 1000nm, about 380 nm to about 1000 nm, about 390 nm to about 1000 nm, about400 nm to about 1000 nm, about 410 nm to about 1000 nm, about 420 nm toabout 1000 nm, about 430 nm to about 1000 nm, about 440 nm to about 1000nm, about 450 nm to about 1000 nm, about 460 nm to about 1000 nm, about470 nm to about 1000 nm, about 480 nm to about 1000 nm, about 490 nm toabout 1000 nm, about 500 nm to about 1000 nm, about 510 nm to about 1000nm, about 520 nm to about 1000 nm, about 530 nm to about 1000 nm, about540 nm to about 1000 nm, about 550 nm to about 1000 nm, about 560 nm toabout 1000 nm, about 570 nm to about 1000 nm, about 580 nm to about 1000nm, about 590 nm to about 1000 nm, about 600 nm to about 1000 nm, about610 nm to about 1000 nm, about 620 nm to about 1000 nm, about 630 nm toabout 1000 nm, about 640 nm to about 1000 nm, about 650 nm to about 1000nm, about 660 nm to about 1000 nm, about 670 nm to about 1000 nm, about680 nm to about 1000 nm, about 690 nm to about 1000 nm, about 700 nm toabout 1000 nm, about 710 nm to about 1000 nm, about 720 nm to about 1000nm, about 730 nm to about 1000 nm, about 740 nm to about 1000 nm, about750 nm to about 1000 nm, about 760 nm to about 1000 nm, about 770 nm toabout 1000 nm, about 780 nm to about 1000 nm, about 790 nm to about 1000nm, about 800 nm to about 1000 nm, about 810 nm to about 1000 nm, about820 nm to about 1000 nm, about 830 nm to about 1000 nm, about 840 nm toabout 1000 nm, about 850 nm to about 1000 nm, about 860 nm to about 1000nm, about 870 nm to about 1000 nm, about 880 nm to about 1000 nm, about890 nm to about 1000 nm, about 900 nm to about 1000 nm, about 910 nm toabout 1000 nm, about 920 nm to about 1000 nm, about 930 nm to about 1000nm, about 940 nm to about 1000 nm, about 950 nm to about 1000 nm, about960 nm to about 1000 nm, about 970 nm to about 1000 nm, about 980 nm toabout 1000 nm, about 990 nm to about 1000 nm, about 100 nm to about 990nm, about 100 nm to about 980 nm, about 100 nm to about 970 nm, about100 nm to about 960 nm, about 100 nm to about 950 nm, about 100 nm toabout 940 nm, about 100 nm to about 930 nm, about 100 nm to about 920nm, about 100 nm to about 910 nm, about 100 nm to about 900 nm, about100 nm to about 890 nm, about 100 nm to about 880 nm, about 100 nm toabout 870 nm, about 100 nm to about 860 nm, about 100 nm to about 850nm, about 100 nm to about 840 nm, about 100 nm to about 830 nm, about100 nm to about 820 nm, about 100 nm to about 810 nm, about 100 nm toabout 800 nm, about 100 nm to about 790 nm, about 100 nm to about 780nm, about 100 nm to about 770 nm, about 100 nm to about 760 nm, about100 nm to about 750 nm, about 100 nm to about 740 nm, about 100 nm toabout 730 nm, about 100 nm to about 720 nm, about 100 nm to about 710nm, about 100 nm to about 700 nm, about 100 nm to about 690 nm, about100 nm to about 680 nm, about 100 nm to about 670 nm, about 100 nm toabout 660 nm, about 100 nm to about 650 nm, about 100 nm to about 640nm, about 100 nm to about 630 nm, about 100 nm to about 620 nm, about100 nm to about 610 nm, about 100 nm to about 600 nm, about 100 nm toabout 590 nm, about 100 nm to about 580 nm, about 100 nm to about 570nm, about 100 nm to about 560 nm, about 100 nm to about 550 nm, about100 nm to about 540 nm, about 100 nm to about 530 nm, about 100 nm toabout 520 nm, about 100 nm to about 510 nm, about 100 nm to about 500nm, about 100 nm to about 490 nm, about 100 nm to about 480 nm, about100 nm to about 470 nm, about 100 nm to about 460 nm, about 100 nm toabout 450 nm, about 100 nm to about 440 nm, about 100 nm to about 430nm, about 100 nm to about 420 nm, about 100 nm to about 410 nm, about100 nm to about 400 nm, about 100 nm to about 390 nm, about 100 nm toabout 380 nm, about 100 nm to about 370 nm, about 100 nm to about 360nm, about 100 nm to about 350 nm, about 100 nm to about 340 nm, about100 nm to about 330 nm, about 100 nm to about 320 nm, about 100 nm toabout 310 nm, about 100 nm to about 300 nm, about 100 nm to about 290nm, about 100 nm to about 280 nm, about 100 nm to about 270 nm, about100 nm to about 260 nm, about 100 nm to about 250 nm, about 100 nm toabout 240 nm, about 100 nm to about 230 nm, about 100 nm to about 220nm, about 100 nm to about 210 nm, about 100 nm to about 200 nm, about100 nm to about 190 nm, about 100 nm to about 180 nm, about 100 nm toabout 170 nm, about 100 nm to about 160 nm, about 100 nm to about 150nm, about 100 nm to about 140 nm, about 100 nm to about 130 nm, about100 nm to about 120 nm, or about 100 nm to about 110 nm.

According to any embodiment of the present application, the silica corehas a mean particle diameter of about 55 nm to about 500 nm, about 60 nmto about 500 nm, about 65 nm to about 500 nm, about 70 nm to about 500nm, about 75 nm to about 500 nm, about 80 nm to about 500 nm, about 85nm to about 500 nm, about 90 nm to about 500 nm, about 95 nm to about500 nm, about 100 nm to about 500 nm, about 110 nm to about 500 nm,about 120 nm to about 500 nm, about 130 nm to about 500 nm, about 140 nmto about 500 nm, about 150 nm to about 500 nm, about 160 nm to about 500nm, about 170 nm to about 500 nm, about 180 nm to about 500 nm, about190 nm to about 500 nm, about 200 nm to about 500 nm, about 210 nm toabout 500 nm, about 220 nm to about 500 nm, about 230 nm to about 500nm, about 240 nm to about 500 nm, about 250 nm to about 500 nm, about260 nm to about 500 nm, about 270 nm to about 500 nm, about 280 nm toabout 500 nm, about 290 nm to about 500 nm, about 300 nm to about 500nm, about 310 nm to about 500 nm, about 320 nm to about 500 nm, about330 nm to about 500 nm, about 340 nm to about 500 nm, about 350 nm toabout 500 nm, about 360 nm to about 500 nm, about 370 nm to about 500nm, about 380 nm to about 500 nm, about 390 nm to about 500 nm, about400 nm to about 500 nm, about 410 nm to about 500 nm, about 420 nm toabout 500 nm, about 430 nm to about 500 nm, about 440 nm to about 500nm, about 450 nm to about 500 nm, about 460 nm to about 500 nm, about470 nm to about 500 nm, about 480 nm to about 500 nm, about 490 nm toabout 500 nm, about 50 nm to about 490 nm, about 50 nm to about 480 nm,about 50 nm to about 470 nm, about 50 nm to about 460 nm, about 50 nm toabout 450 nm, about 50 nm to about 440 nm, about 50 nm to about 430 nm,about 50 nm to about 420 nm, about 50 nm to about 410 nm, about 50 nm toabout 400 nm, about 50 nm to about 390 nm, about 50 nm to about 380 nm,about 50 nm to about 370 nm, about 50 nm to about 360 nm, about 50 nm toabout 350 nm, about 50 nm to about 340 nm, about 50 nm to about 330 nm,about 50 nm to about 320 nm, about 50 nm to about 310 nm, about 50 nm toabout 300 nm, about 50 nm to about 290 nm, about 50 nm to about 280 nm,about 50 nm to about 270 nm, about 50 nm to about 260 nm, about 50 nm toabout 250 nm, about 50 nm to about 240 nm, about 50 nm to about 230 nm,about 50 nm to about 220 nm, about 50 nm to about 210 nm, about 50 nm toabout 200 nm, about 50 nm to about 190 nm, about 50 nm to about 180 nm,about 50 nm to about 170 nm, about 50 nm to about 160 nm, about 50 nm toabout 150 nm, about 50 nm to about 140 nm, about 50 nm to about 130 nm,about 50 nm to about 120 nm, about 50 nm to about 110 nm, about 50 nm toabout 100 nm, about 50 nm to about 95 nm, about 50 nm to about 90 nm,about 50 nm to about 85 nm, about 50 nm to about 80 nm, about 50 nm toabout 75 nm, about 50 nm to about 70 nm, about 50 nm to about 65 nm,about 50 nm to about 60 nm, or about 50 nm to about 55 nm.

According to any embodiment of the present application, the catalyticmetal nanoparticle has a mean particle diameter of about 2 nm to about10 nm, about 3 nm to about 10 nm, about 4 nm to about 10 nm, about 5 nmto about 10 nm, about 6 nm to about 10 nm, about 7 nm to about 10 nm,about 8 nm to about 10 nm, about 9 nm to about 10 nm, about 1 nm toabout 9 nm, about 1 nm to about 8 nm, about 1 nm to about 7 nm, about 1nm to about 6 nm, about 1 nm to about 5 nm, about 1 nm to about 4 nm,about 1 nm to about 3 nm, or about 1 nm to about 2 nm.

According to any embodiment of the present application, the mesoporoussilica shell has a thickness of about 55 nm to about 500 nm, about 60 nmto about 500 nm, about 65 nm to about 500 nm, about 70 nm to about 500nm, about 75 nm to about 500 nm, about 80 nm to about 500 nm, about 85nm to about 500 nm, about 90 nm to about 500 nm, about 95 nm to about500 nm, about 100 nm to about 500 nm, about 110 nm to about 500 nm,about 120 nm to about 500 nm, about 130 nm to about 500 nm, about 140 nmto about 500 nm, about 150 nm to about 500 nm, about 160 nm to about 500nm, about 170 nm to about 500 nm, about 180 nm to about 500 nm, about190 nm to about 500 nm, about 200 nm to about 500 nm, about 210 nm toabout 500 nm, about 220 nm to about 500 nm, about 230 nm to about 500nm, about 240 nm to about 500 nm, about 250 nm to about 500 nm, about260 nm to about 500 nm, about 270 nm to about 500 nm, about 280 nm toabout 500 nm, about 290 nm to about 500 nm, about 300 nm to about 500nm, about 310 nm to about 500 nm, about 320 nm to about 500 nm, about330 nm to about 500 nm, about 340 nm to about 500 nm, about 350 nm toabout 500 nm, about 360 nm to about 500 nm, about 370 nm to about 500nm, about 380 nm to about 500 nm, about 390 nm to about 500 nm, about400 nm to about 500 nm, about 410 nm to about 500 nm, about 420 nm toabout 500 nm, about 430 nm to about 500 nm, about 440 nm to about 500nm, about 450 nm to about 500 nm, about 460 nm to about 500 nm, about470 nm to about 500 nm, about 480 nm to about 500 nm, about 490 nm toabout 500 nm, about 50 nm to about 490 nm, about 50 nm to about 480 nm,about 50 nm to about 470 nm, about 50 nm to about 460 nm, about 50 nm toabout 450 nm, about 50 nm to about 440 nm, about 50 nm to about 430 nm,about 50 nm to about 420 nm, about 50 nm to about 410 nm, about 50 nm toabout 400 nm, about 50 nm to about 390 nm, about 50 nm to about 380 nm,about 50 nm to about 370 nm, about 50 nm to about 360 nm, about 50 nm toabout 350 nm, about 50 nm to about 340 nm, about 50 nm to about 330 nm,about 50 nm to about 320 nm, about 50 nm to about 310 nm, about 50 nm toabout 300 nm, about 50 nm to about 290 nm, about 50 nm to about 280 nm,about 50 nm to about 270 nm, about 50 nm to about 260 nm, about 50 nm toabout 250 nm, about 50 nm to about 240 nm, about 50 nm to about 230 nm,about 50 nm to about 220 nm, about 50 nm to about 210 nm, about 50 nm toabout 200 nm, about 50 nm to about 190 nm, about 50 nm to about 180 nm,about 50 nm to about 170 nm, about 50 nm to about 160 nm, about 50 nm toabout 150 nm, about 50 nm to about 140 nm, about 50 nm to about 130 nm,about 50 nm to about 120 nm, about 50 nm to about 110 nm, about 50 nm toabout 100 nm, about 50 nm to about 95 nm, about 50 nm to about 90 nm,about 50 nm to about 85 nm, about 50 nm to about 80 nm, about 50 nm toabout 75 nm, about 50 nm to about 70 nm, about 50 nm to about 65 nm,about 50 nm to about 60 nm, or about 50 nm to about 55 nm.

According to any embodiment of the present application, the mesoporoussilica shell has a pore diameter of about 2 nm to about 10 nm, about 3nm to about 10 nm, about 4 nm to about 10 nm, about 5 nm to about 10 nm,about 6 nm to about 10 nm, about 7 nm to about 10 nm, about 8 nm toabout 10 nm, about 9 nm to about 10 nm, about 1 nm to about 9 nm, about1 nm to about 8 nm, about 1 nm to about 7 nm, about 1 nm to about 6 nm,about 1 nm to about 5 nm, about 1 nm to about 4 nm, about 1 nm to about3 nm, or about 1 nm to about 2 nm.

The above disclosure is general. A more specific description is providedbelow in the following examples. The examples are described solely forthe purpose of illustration and are not intended to limit the scope ofthe present application. Changes in form and substitution of equivalentsare contemplated as circumstances suggest or render expedient. Althoughspecific terms have been employed herein, such terms are intended in adescriptive sense and not for purposes of limitation.

EXAMPLES

General Methods and Techniques

Solid State NMR

¹³C cross-polarization (CP) and directly-excited (Bloch decay)magic-angle-spinning (MAS) NMR spectra were acquired using a 600 MHzVarian NMR system equipped with a 3.2-mm double-resonance probe. Thesamples were tightly-packed into 3.2-mm pencil-type rotors and spun to16 kHz. The Bloch decay spectra were acquired using a 5 μs ¹³Cexcitation pulse and a 10 s recycle delay while the CPMAS experimentsused a 3.2 μs ¹H excitation pulse, a 1 ms contact time, and a 5 srecycle delay. High powered (80 kHz) SPINAL-64 decoupling was applied inall experiments and the resolution was found to be limited by the¹³C-¹³C homonuclear dipolar coupling interactions, with faster spinningyielding an improved resolution. The number of scans totaled 128(92) forthe mSiO₂, 47126(47126) for the silica gel, 128(288) for the 200 nmStöber silica, and 4096(1306) for the 50 nm Stöber silica, with thefirst number being that for the CPMAS experiment and second beingassociated with the Bloch decay. 8320 scans were accumulated for theBloch decay spectrum of the non-enriched 7 kg/mol PE on the mSiO₂. 8192scans were accumulated in the case of the mSiO₂ that was dried at 300°C. under vacuum. Chemical shifts were referenced to DSS(4,4-dimethyl-4-silapentane-1-sulfonic acid) using the universalshielding scale.

The two-dimensional ¹³C exchanged spectroscopy (EXSY) spectra wereacquired using a 400 MHz Agilent DD2 solid-state NMR spectrometerequipped with a 3.2-mm MAS probe. Samples were spun to a MAS rate of 15kHz. 2.5 s ¹³C π/2 pulses were used. A presaturation loop consisting of50 pairs of alternating 0° and 900 phased pulses was applied prior to arecovery period, which was set to 3 s. ¹H SPINAL-64 decoupling (100 kHz)was applied during the t₁ evolution period and the acquisition. Mixingtimes varied between 0 and 4 s. Experiments were conducted at 72, 93,and 114° C. The exact temperatures were determined via ex situmeasurement of the change in the chemical shift of Pb(NO₃)₂ with respectto the static spectrum collected at 25° C. The observed temperaturestake into account sample heating due to MAS. The number of scans and t₁increments varied between 64 to 192 and 64 to 88, respectively. Greaternumbers of scans and t₁ increments were used for the higher temperatureexperiments.

Electron Microscopy

Transmission electron microscopy (TEM) images were obtained on a TecnaiG2 F20 electron microscope operated at 200 kV. High-angle annulardark-field scanning transmission electron microscopy (HAADF-STEM) imagewas acquired using a FEI Titan Themis 300 probe-corrected scanningtransmission electron microscope under 200 kV accelerating voltage.

Dynamic Light Scattering

Dynamic light scattering for particle size determination was recordedusing a Malvern Zetasizer Nano ZS100 with MPT-2 autotitrator withethanol as the solvent.

X-Ray Diffraction

Powder X-ray diffraction (PXRD) patterns were measured by a Bruker D8Advance Twin diffractometer with Cu K_(α) radiation (40 kV, 40 mA,λ=0.1541 nm).

Nitrogen Adsorption

N₂ physisorption experiments, Brunauer-Emmett-Teller (BET) surface areaanalysis, and Barrett-Joyner-Halenda (BJH) mesopore size analysis wereconducted using a Micromeritics 3Flex surface characterization analyzerat 77 K.

Elemental Analysis

The Pt NP loadings for the catalysts were determined by inductivelycoupled plasma mass spectrometry (ICP-MS; Thermo Scientific X SeriesII). The samples are first treated with hydrofluoric acid (50 μL,48-51%, Acros Organics) to etch away silica and then digested with aquaregia (4 mL). The final solution is diluted with 2 v/v % nitric acid totarget concentrations.

Gel Permeation Chromatography

High temperature gel permeation chromatography (HT-GPC) was performed onan Agilent PL-GPC 220 equipped with a refractive index (RI) detector andthree PL-Gel Mixed B columns. GPC columns were eluted at 1.0 mL/min with1,2,4-trichlorobenzene (TCB) containing 0.01 wt. %di-tert-butylhydroxytoluene (BHT) at 150° C. The samples were preparedin TCB (with BHUT) at a concentration of 1.0 mg/ML unless otherwisestated and heated at 150° C. for at least 1 h prior to injection. HT-GPCdata calibration was done with monomodal polyethylene standards fromVarian and Polymer Standards Service.

Gas Chromatography Flame Ionization Detection (GC-FID). Gaschromatography (GC) analyses were performed on an Agilent 6890 gaschromatograph equipped with a split/splitless injector and a flameionization detector (FID). The column was a 30 m×0.32 mm HP-5 (Agilent)with a film thickness of 0.25 μm. These experiments were performed toestablish the reproducibility of the GC methods on separate instrumentsand to compare with GC data detected using MS. Separations wereperformed under temperature-programmed conditions from 60 to 325° C. at4.0° C./min with initial and final hold times of 2 and 10 minutes,respectively. Helium carrier gas was employed with a constant flow of4.5 mL/min. Injector and detector temperatures were maintained at 320and 345° C., respectively. In initial studies, oil samples extractedwith dichloromethane after 24 h of hydrogenolysis were taken up indichloromethane and 1 μL of solution was injected (splitless mode). Thesolvent vent time was 2 minutes. In subsequent analyses, the residue wastaken up in a mixture consisting of 2 parts dichloromethane and 1 parttoluene, and 4 μL was injected (split mode) with a split ratio of 10:1.Blank injections (dichloromethane only) were included between eachexperiment to ensure residual hydrocarbons are were not present on thecolumn. Retention times of known species, including pure C₂₈H₅₈(octacosane, Sigma-Aldrich, 0504) and an American Society for Testingand Material's 20 component (Restek ASTM D2287-12 STANDARD) test mixtureof saturated alkanes dissolved in dichloromethane, were used to identifythe species in catalytic reaction mixtures.

Example 1—Synthesis of Polymer and Inorganic Catalytic Materials

mSiO₂

Decyltrimethylammonium bromide (C10TAB, 0.74 mmol) was dissolved inultrapure water (480 mL). 2 M NaOH (3.5 mL) was added, and the solutionwas stirred at 80° C. for 1 h. Tetraethyl orthosilicate (TEOS, 5.0 mL)was added in dropwise fashion over 5 min. The mixture was stirred at 80°C. for 2 h to provide a white suspension. The solution was filteredusing a filter frit, and the solid was washed with water (1×200 mL) andthen methanol (3×200 mL). The solid was allowed to dry on the filter atroom temperature, and then the solid was dried under vacuum. The driedsample (1.0 g) was suspended in acidic methanol (100 mL) with 12 N HCl(0.8 mL), and the suspension was then heated at reflux (80° C.) for 6 h.The solid was isolated by filtration, washed with water (3×200 mL) andmethanol (3×200 mL), and then dried under vacuum. The datacharacterizing the mSiO₂ material is given below.

50 nm Stöber Silica

Ethanol (200 proof, 190 mL) was mixed with water (10 mL) and NH₃·H₂O(˜28 wt %, 5 mL). This solution was equilibrated at 40° C. for 1 h. TEOS(2.75 mL) was then added to the solution at 40° C., and the reactionmixture was maintained at 40° C. for 2 h. The silica spheres wereseparated by centrifugation and washed with ethanol (3×100 mL). The datacharacterizing the 50 nm particles of Stöber silica is given below.

127 nm Stöber Silica

127 nm SiO₂ spheres were prepared using the Stöber method. The abovesolution of 45 nm seed particles (1 mL) was mixed with deionized water(2.6 mL), ethanol (18 mL), and NH₃·H₂O (˜28 wt %, 1.7 mL). The mixturewas stirred at 500 rpm for 1 h at room temperature. Three portions ofTEOS (1.5 mL total volume) were added in a dropwise fashion to thesolution, with 30 min intervals between the addition of each portion.The reaction was stirred at room temperature for 6 h. The SiO₂ sphereswere then washed with an ethanol/water solution (50/50 v/v; 5×20 mL) andthen dried under vacuum at room temperature. The data characterizing the127 nm particles of Stöber silica is given below.

200 nm Stöber Silica

200 nm SiO₂ spheres were synthesized by a four-step seeded growthapproach. First, 24 nm SiO₂ seeds were prepared. For this, L-arginine(18.2 mg) and ultrapure water (13.9 mL) were thoroughly mixed. Then,cyclohexane (0.9 mL) was added gently to the water-arginine mixture tolayer the cyclohexane on top of the aqueous solution. The solution washeated to 60.0±0.2° C. for 30 min with stirring at 300 rpm. TEOS (1.10mL) was added to the mixture. The reaction was allowed to proceed for 20h at 60° C. After this time, the aqueous layer (bottom) was separatedfrom the organic layer and stored in a refrigerator.

These 24 nm SiO₂ seed particles were then used for the synthesis of 45nm SiO₂ seed particles. The 24 nm seed suspension (4 mL) was dilutedwith ultrapure water (14.4 mL). Cyclohexane (2 mL) was then added tothis solution. The mixture was heated at 60° C. for 30 min with stirringat 300 rpm. TEOS (1.408 mL) was then immediately added to the top layer,and the mixture was allowed to stand at 60° C. for 30 h. After thistime, the bottom layer was separated and stored in a refrigerator.

82 nm SiO₂ seed particles were then grown using the Stöber method,initiated from the 45 nm seed particles (1 mL). The above solution wasdiluted with deionized water (2.6 mL) and ethanol (18 mL). Subsequently,NH₃·H₂O (˜28 wt %, 1.7 mL) was added to the solution. The solution wasstirred at 500 rpm for 1 h at room temperature. Three portions of TEOS(0.8 mL total) were added in a dropwise fashion to the solution, with 30min intervals between the addition of each portion. The solution wasthen stirred for 6 h and stored in the refrigerator.

Finally, 200 nm SiO₂ spheres were prepared as follows: the solution of82 nm seed particles (1 mL) was diluted with deionized water (2.6 mL)and ethanol (18 mL). NH₃·H₂O (˜28 wt %, 1.7 mL) was then added to thesolution, which was mixed at 500 rpm for 1 h. Two portions of TEOS (0.44mL total) were added dropwise to the solution, with 30 min intervalsbetween the addition of each portion. The reaction mixture was stirredfor 6 h. After 6 h, 200 nm SiO₂ spheres were obtained and stored in therefrigerator for further use. The SiO₂ spheres were then washed with anethanol/water solution (50/50 v/v; 5×20 mL) and then dried under vacuumat room temperature. The data characterizing the 200 nm particles ofStöber silica is given below.

Pt Nanoparticles

K₂PtCl₄ (41.5 mg), tetradecyltrimethylammonium bromide (C₁₄TAB, 505 mg),and polyvinylpyrrolidone (PVP-K30, M_(w)=40,000, 222 mg) were added toethylene glycol (20 mL). The atmosphere of the vessel was inertized withAr, and the solution was heated at 140° C. for 2 h. Acetone (180 mL) wasadded to precipitate “as prepared” Pt NPs. The precipitate was furtherwashed with an ethanol/hexane mixture (1/4 v/v; 5×20 mL), and ethanol(20 mL) was added to the material for storage.

Pt SiO₂

In a typical synthesis, SiO₂ (1 g) spheres were dispersed in isopropanol(175 mL). A solution of 3-aminopropyl triethoxysilane (APTS, 200 μL) inisopropanol (25 mL) was added to this dispersion to functionalize thesilica spheres with NH₂ groups. The reaction mixture was allowed to ageat 80° C., and then the SiO₂ spheres were washed with ethanol (3×20 mL)by centrifugation at 8000 rpm. The NH₂-functionalized SiO₂ spheres werethen dried under vacuum at room temperature and annealed at 100° C. inair for 5 h.

NH₂-functionalized SiO₂ spheres (400 mg) were dispersed in ethanol (120mL). 3.2±0.5 nm Pt nanoparticles suspended in ethanol (220 mL) wereadded in a dropwise fashion to a vigorously stirred dispersion ofNH₂-functionalized SiO₂ spheres. The resulting mixture of SiO₂-supportedPt nanoparticles (Pt/SiO₂) was sonicated for 30 min. The Pt/SiO₂ sphereswere separated from the solution by centrifugation at 8000 rpm andwashed with ethanol (5×30 mL).

mSiO₂/Pt/SiO₂ with 1.7 nm Pores

Pt/SiO₂ spheres (25 mg) were dispersed in ethanol (10 mL) by sonicationfor 0.5 h at room temperature. A premixed solution ofdodecyltrimethylammonium bromide (C₁₂TAB, 132 mg) in H₂O (50 mL) andethanol (16.3 mL) was added to the above Pt/SiO₂ dispersion, and themixture was sonicated for another 0.5 h. NH₃·H₂O (˜28 wt %, 550 μL) wasthen added to the solution. After 0.5 h of gentle stirring, a solutionof TEOS (600 μL) in ethanol (5 mL) was added to the above solution in adropwise manner in 4 portions (150 μL each) every 0.5 h. The solutionwas stirred for 6 h at room temperature. The mSiO₂/Pt/SiO₂ particleswere separated by centrifugation, washed with ethanol (3×20 mL), andfinally dispersed into a mixture of methanol (15 mL) and concentratedhydrochloric acid (1 mL). This mixture was heated at reflux (80° C.) for24 h to remove the C₁₂TAB surfactant. After refluxing, mSiO₂/Pt/SiO₂catalysts were washed thoroughly with ethanol (6×15 mL) bycentrifugation at 8000 rpm.

mSiO₂/Pt/SiO₂ with 2.4 nm Pores

Pt/SiO₂ spheres (25 mg) were dispersed in ethanol (10 mL) by sonicationfor 30 min at room temperature. A premixed solution ofhexadecyltrimethylammonium bromide (C₁₆TAB, 165 mg) in H₂O (50 mL) andethanol (16.3 mL) was added to the above Pt/SiO₂ dispersion, and themixture was sonicated for another 30 min. Then 550 μL of concentratedNH₃·H₂O (˜28 wt %) was added to the solution. After 30 min of gentlestirring, a solution of TEOS (720 μL) in ethanol (5 mL) was added to theabove solution in a dropwise manner (4×180 μL) every 30 min. Thesolution was stirred for 6 h at room temperature. The mSiO₂/Pt/SiO₂particles were separated on a centrifuge, washed with ethanol (3×20 mL),and finally dispersed into a mixture of methanol (15 mL) andconcentrated hydrochloric acid (1 mL). This mixture was heated at reflux(80° C.) for 24 h to remove the C₁₆TAB surfactant. After refluxing,mSiO₂/Pt/SiO₂ catalysts were washed thoroughly with ethanol (6×15 mL) bycentrifugation at 8000 rpm.

mSiO₂/Pt/SiO₂ with 3.5 nm Pores

This catalyst was prepared in the same way as the 2.4 nm-poremSiO₂/Pt/SiO₂ catalyst given in the main text, except n-hexane (20 mL)was added to the mixture priory to the TEOS addition, and the shellgrowth time was increased from 6 h to 12 h.

Pt/MCM-41

200 mg MCM-41 was dispersed in Milli-Q water (10 mL) by sonicating for0.5 h, then H₂PtCl₆ (4.1 mg) was added to the solution. The reactionmixture was heated at 60° C. in an oil bath and stirred at 300 rpm for12 h until the water completely evaporated. The resulting powder wasreduced at 220° C. for 2 h under 10% H₂/Ar (5/45 mL/min) in a tubefurnace.

Pt/SBA-15

K₂PtCl₄ (4.1 mg) was dissolved into Milli-Q water (420 μL). Half of thesolution (210 L) was added dropwise onto the SBA-15 powder (200 mg) withstirring. The mixture was allowed to stand for 12 h and then was driedunder reduced pressure. After drying, this procedure was repeated withthe other portion of the K₂PtCl₄ solution (210 μL). The dried powder wasreduced at 220° C. for 2 h under 10% H₂/Ar (5/45 mL/min) in a tubefurnace.

NiMo γ-Al₂O₃

Ni(NO₃)₂ (139.4 mg) and (NH₄)₆Mo₇O₂₄·4H₂O (59.8 mg) were dissolved inMilli-Q water (380 μL). Half of the solution (190 μL) was added dropwiseonto the γ-Al₂O₃ powder (200 mg, Alfa Aesar) with stirring. The mixturewas allowed to stand for 12 h and then was dried under reduced pressure.After drying, this procedure was repeated with the second portion ofsolution (190 μL). The dried powder was calcined at 973 K for 6 h in amuffle furnace.

Catalyst Data

FIG. 7 shows the TEM images of the three samples, (a) mSiO₂, (b) 50 nmStöber silica, and (c) 200 nm Stöber silica prior to polyethyleneadsorption. All samples show uniform spherical shapes and are relativelymonodisperse. The respective diameters for the mSiO₂ and the 50 and 200nm Stöber silica particles were measured to be 488±24 (5.0%), 50.1±5.7(11.3%), and 221.1±5.7 (2.6%) nm. An enlarged view of the mSiO₂ is shownin FIG. 8 .

FIG. 9 shows the TEM images of the 127 nm Stöber SiO₂ spheres and thecorresponding Pt/SiO₂ and mSiO₂/Pt/SiO₂. All samples are relativelymonodispersed and uniform. The diameter of the 127 nm Stöber silicaparticles is 127±7 (5.5%) nm and the thickness of the mesoporous shellfor core-shell material structure is 110±8 (7.2%) nm. The average porediameter for the mesoporous shell is 2.4 nm. FIG. 10 shows TEM images ofthe mSiO₂/Pt/SiO₂ with average 1.7 and 3.5 nm-diameter pores in themesoporous shell. The mesoporous shells are 97±8 and 115±5 nm thick forthe 1.7 and 3.5 nm-diameter pore mSiO₂/Pt/SiO₂, respectively. FIG. 11shows the TEM images of Pt/SBA-15, Pt/MCM-41, and NiMo/γ-Al₂O₃.

The DLS sizes of the mSiO₂, the 50 Stöber silica, and 200 nm Stöbersilica were 190, 96, and 241 nm, respectively. These sizes are inagreement with those determined by TEM with the minor difference beingattributed to the ethanol solvation environment. The DLS size ofC₁₀TAB-produced mSiO₂ is nevertheless significantly smaller than theirgeometric sizes determined by TEM, likely due to their mesoporoussurface.

FIG. 12 shows the typical low angle diffraction peak of MCM-type mSiO₂.

Nitrogen physisorption results are listed in Tables 1 and 2 below, andthe isotherms are shown in FIGS. 13, 15, 17, and 19 with the pore sizedistributions shown in FIGS. 14, 16, 18, and 20 . The mSiO₂ (used in ¹³CSSNMR experiments) have a large surface area and a high mesoporositywith a uniform pore size of 1.5 nm. The Stöber silicas have a lowsurface area with almost no pores (the broad peak at 50 nm is likely dueto the interparticle assembly), in agreement with their solidmorphology. The Davisil silica gel has a moderate surface area that isin between those measured for the Stöber silicas and the mSiO₂. ThemSiO₂/Pt/SiO₂ (1.7, 2.4, and 3.5 nm pore) catalysts have large surfacearea as well. For mSiO₂/Pt/SiO₂ with 2.4 nm pores, loading the Pt ontothe core-shell structure only slightly changes the surface area incomparison to mSiO₂/SiO₂ (2.4 nm pore). Pt/SBA-15, Pt/MCM-41, andNiMo/γ-Al₂O₃ have BET surface areas of 980, 1030, and 190 m²/g,respectively. The averaged pore diameters for Pt/SBA-15, Pt/MCM-41, andNiMo/γ-Al₂O₃ are 7.7, 2.0, and 8.2 nm, respectively.

TABLE 1 N₂ physisorption data silica materials used in PE adsorption ¹³CNMR studies. BET BJH surface pore pore TEM DLS area volume size sizessizes sample (m²/g) (cm³/g) (nm) (nm) (nm) mSiC₂ 1420 0.83 1.5 448 (24)190 silica gel-Davisil 480 0.75 12.0 2500-5000^(a) ND 50 nm Stöber SiO₂55 NA NA 50.1 (5.7)  96 200 nm Stöber SiO₂ 14 NA NA 221.1 (5.7) 241^(a)Size as reported by vendor (Aldrich).

TABLE 2 N₂ Physisorption data for hydrogenolysis catalysts. BET BJHsurface pore pore TEM area volume size sizes sample (m²/g) (cm³/g) (nm)(nm) 127 nm SiO₂  30 0.03 NA 127(7)  mSiO₂/SiO₂ (2.4 nm pore) 1110 0.862.4 337(10) mSiO₂/Pt/SiO₂ (2.4 nm pore) 1070 0.84 2.4 342(11)mSiO₂/Pt/SiO₂ (1.7 nm pore) 1300 0.66 1.7 313(12) mSiO₂/Pt/SiO₂ (3.5 nmpore) 1060 1.22 3.5 350(10)¹³C-Enriched Polyethylene

C₂H₄ (99% enriched 1,2-¹³C₂) was obtained from Cambridge Isotope Lab ina 250 mL glass vessel and used without purification. Methylaluminoxane(MAO) was obtained from Sigma-Aldrich as a 10 wt % solution in toluene;the volatile materials were evaporated, and the white solid MAO residuewas washed with pentane (5×10 mL) to give a shiny white solid afterexhaustive drying. The {κ²-N(C₆F₅)=CHC₆H₂tBu₂O}₂TiCl₂ polymerizationcatalyst was synthesized following the literature procedure.

¹³C-labeled polyethylene was prepared by the following procedure: ASchlenk round bottom flask was charged with a toluene solution (50 mL)of MAO (0.044 g, 0.74 mmol). 1,2-¹³C₂H₄ (250 mL at 1 atm) was condensedinto the reaction vessel cooled in a liquid nitrogen bath. The vesselwas sealed and allowed to warm to room temperature, and then the mixturewas cooled to 0° C. The Ti-phenoxyimine catalyst (0.002 g, 0.002 mmol),dissolved in a minimal amount of toluene, was added to the reactionmixture through a septum. The resulting solution was stirred at 0° C.for 10 min and then allowed to warm to room temperature. Stirring wascontinued for 30 min at room temperature. The solution was then pouredinto a 5% HCl in MeOH solution to precipitate the polymer. Theprecipitate was isolated by filtration and dried under reduced pressureto yield ¹³C-labeled polyethylene as a white solid (0.43 g). The polymerwas characterized by HT-GPC (M_(n)=132,000 kg/mol; M_(w)=429,800;Ð=3.2).

Example 2—General Description of Hydrogenolysis Examples

PE hydrogenolysis experiments were performed in Parr autoclaves with anoverhead mechanical stirrer adapted with an impeller for mixing viscoussuspensions. HDPE (3 g, M_(n)=5,900) and catalyst (0.0013 Pt wt % withrespect to PE) were loaded into a glass-lined autoclave, which wassealed and refilled using alternating vacuum and argon cycles (3×). Thereactor was then pressurized with H₂ (120 psi), mixed, and heated at250° C. The pressure at 250° C. is 200 psi. After a designated time, thereactor was allowed to cool, and the pressure was released. The gaseousportion was analyzed by GC-MS. The mass of the products was measured todetermine conversion to gaseous products, and the solid residue wasextracted with methylene chloride (3×20 mL) at 100° C. with mixing.Methylene chloride extracts were combined and concentrated to provide awaxy oil product, which was analyzed by GC-MS and GC-FID, and theremaining insoluble residue was analyzed by HT-GPC.

HDPE and the catalytic materials (either mSiO₂/Pt/SiO₂, Pt/SiO₂, ormSiO₂/SiO₂) were physically mixed and then placed in a glass-lined Parrautoclave reactor equipped with a mechanical impeller-style stirrer. Thereactor atmosphere was cycled between Ar and vacuum three times, andthen the reactor was filled with H₂ (120 psi) and sealed. The reactorwas placed in a heating mantle and heated to 250° C. for thepredetermined time (6, 24 or 48 h); under these conditions the pressurereading is 200 psi. After a designated time, the reactor was vented, thegaseous portion was analyzed by GC-MS, and the reactor was allowed tocool. (In complementary experiments, the reactor was allowed to cool,then the reactor was vented, and the gaseous products were analyzed byGC-MS; this was done to ensure that the overall yields and distributionsof low molecular weight products were not affected by workup andanalysis protocols). The mass of the gaseous products was determined bytaking the difference of the combined masses of the solid residue,impeller and glass reaction liner before and after the reaction. Asample of the solid residue was removed for analysis by HT-GPC. Thesolid residue was extracted with methylene chloride (3×20 mL) at 80° C.with mixing. Methylene chloride extracts were combined and concentratedto provide a waxy oil product, which was analyzed by GC-MS.

Molecular Weight Data

The polymeric residues produced from the catalytic hydrogenolysisreactions were analyzed by HT-GPC. A sample of the crude reactionmixture was dissolved in TCB and analyzed by HT-GPC directly. Theremaining material was extracted with methylene chloride (as describedabove) to remove the small, soluble products, and the residual solid wasthen dissolved in TCB and analyzed by HT-GPC. These samples werecompared to virgin polyethylene (HDPE) used for the catalyticexperiments, and to ‘virgin HDPE’ that had been extracted with methylenechloride (to match the post-catalysis workup).

Catalytic hydrogenolysis and thermal, catalyst-free reactions of theHDPE result in lower M_(n), which is statistically weighted to emphasizecontributions of lower molecular weight species to the distribution.Once the soluble, small molecule species are extracted into methylenechloride, a comparison of M_(n), Ð (M_(w)/M_(n)), and M_(p) wouldindicate the presence of new, shorter polymeric chains. EquivalentM_(n), Ð, and M values for treated and untreated polymer, aftermethylene chloride extraction of soluble species, would indicate thatthe remaining insoluble chains have not undergone significanthydrogenolysis steps. The HT-GPC data are summarized in Table 3.

TABLE 3 HT-GPC analysis of polymeric solids obtained afterhydrogenolysis (pre-extraction) and residual polymeric materials afterextraction (post-extraction) with methylene chloride at 80° C. Conver-Time sion M_(n) M_(w) Catalyst (h) (%) (kDa) (kDa) Ð HDPE starting — —Pre-extraction 5.9 26.3 4.45 material Post-extraction 6.6 30.0 4.6mSiO₂/Pt/SiO₂ ^(a) 6 6.7 Pre-extraction 3.0 32.2 10.7 Post-extraction6.1 37.3 6.1 Pt@SiO₂ ^(b) 6 8.0 Pre-extraction 5.6 25.4 4.5Post-extraction 6.7 30.5 4.5 mSiO₂/Pt/SiO₂ ^(c) 24 10.3 Pre-extraction4.5 29.9 6.7 Post-extraction 6.8 31.9 4.7 Pt@SiO₂ ^(d) 24 20.3Pre-extraction 4.0 56.3 14.0 Post-extraction 3.7 42.9 11.7 mSiO₂/Pt/SiO₂^(c) 48 24.1 Pre-extraction 4.4 35.2 7.9 Post-extraction 6.3 31.0 4.9Pt@SiO₂ ^(d) 48 27.5 Pre-extraction 3.6 15.5 4.3 Post-extraction 3.917.4 4.5 mSiO₂/SiO₂ 6 3.0 Pre-extraction 4.1 22.5 5.5 (Pt-free)Post-extraction 4.8 21.4 4.5 ^(a)mSiO₂/Pt/SiO₂ catalyst (0.042 Ptwt/silica wt %; 0.00087 Pt wt/HDPE wt %). ^(b)Pt/SiO₂ catalyst (0.478 Ptwt/silica wt %; 0.00099 Pt wt/HDPE wt %). ^(c)mSiO₂/Pt/SiO₂ catalyst(0.06 Pt wt/silica wt %; 0.0013 Pt wt/HDPE wt %). ^(d)Pt/SiO₂ catalyst(1.7 Pt wt/silica wt %; 0.0013 Pt wt/HDPE wt %).Gas Chromatography-Mass Spectrometry (GC-MS)

Headspace analysis. Gas samples taken from the headspace of the Parrreactor were analyzed by the gas chromatography using an AgilentTechnologies 7890A GC system equipped with an Agilent Technologies 5975Cinert MSD mass spectrometer. A capillary column, Agilent J&W DB-5ht[(5%-phenyl)-methylpolysiloxane, 0.25 mm, 30 m, 0.1 μm] was used forcompound separation. Samples were injected manually using a gas-tightsyringe.

Oil analysis. The full description of GC-MS analysis methods isdescribed above. The GC-MS of this calibration mixture is shown in FIG.21 .

The carbon numbers in samples are estimated as follows: A GC-MS of ASTMstandard was integrated. A plot of integrated area vs carbon number(shown in FIG. 22 ) allows the determination of the response of allC_(n)(since ASTM standard does not include C₁₃, C₁₉, C₂₁, etc.) byinterpolation. The regions of C₆-C₂₀ and C₂₀-C₄₀ are linear, but withinequivalent slopes. Therefore, these two regions were fit separately.

The relative mass ratio as a function of carbon number F(C_(n)) wascalculated by dividing the area of each peak (or calculated peaks forthe appropriate range using the linear fits from FIG. 22 ) by that ofthe C₁₂ (which was arbitrarily chosen—note that this protocol was alsotested with C₂₄ and, expectedly, gives an equivalent scaling factors foreach peak).

$\begin{matrix}{{{relative}{mass}{ratio}} = {{F\left( C_{n} \right)} = \frac{{integrated}{peak}{area}{of}C_{n}}{{integrated}{peak}{area}{of}C_{12}}}} & (1)\end{matrix}$

The relative mass ratio for each C_(n) allows estimation of the GC-MSresponse for hydrocarbon species as a function of C_(n). In GC-MS ofcatalytic mixtures below, the observed integrated intensities for eachcarbon number are appropriately scaled based on the relative mass ratio(C_(n)).

$\begin{matrix}{{{relative}{intensity}{for}a{carbon}{number}} = {{G\left( C_{n} \right)} = \frac{{observed}{integrated}{intensity}{of}{catalytic}{sample}}{F\left( C_{n} \right)}}} & (2)\end{matrix}$

The percentage of each carbon number is determined by dividing thatcarbon number's relative intensity by the sum of the relativeintensities for all carbon species observed.

$\begin{matrix}{{\% C_{n}} = {\frac{G\left( C_{n} \right)}{\underset{n = 6}{\sum\limits^{36}}{G\left( C_{n} \right)}} \times 100\%}} & (3)\end{matrix}$Simulated Distillation Gas Chromatography Flame Ionization Detection(SimDist GC-FID)

Simulated distillation gas chromatography (GC) was used to analyze thehigher molecular weight components of oily products, as this method canseparate carbon numbers up to at least C₄₀ and provides complementarydata to GC using a capillary column. SimDist GC-FID analyses wereperformed on an Agilent 7890A gas chromatograph equipped with asplit/splitless injector and a flame ionization detector (FID). Thecolumn was a 5 m×0.53 mm MXT-1HT SimDist (Restek) with a film thicknessof 0.10 μm. Separations were performed under temperature-programmedconditions with the column oven programmed from 35 to 70° C. at 10.0°C./min, 70 to 280° C. at 3° C./min, and then 280 to 430° C. at 15°C./min with initial and final hold times of 0.5 and 10 minutes,respectively. Helium carrier gas was employed with a constant flow of 3mL/min. Injector and detector temperatures were maintained at 350 and430° C., respectively. 1.5 μL of solution was injected in the splitlessmode. The solvent vent time was 2 minutes. A mixture of saturatedalkanes (Restek ASTM D2287-12 STANDARD described above) dissolved indichloromethane was used to identify the species formed in catalyticreactions. A SimDist GC-FID of Restek ASTM D2287-12 STANDARD is shownbelow in FIG. 23 .

Example 3—Polymer Upcycling Catalysis

On the basis of the aforementioned NMR characterization of HDPE chainadsorption and translocation in mSiO₂ pores and motivated by thepotential advantages of processive polymer deconstruction, a catalystwas designed with Pt nanoparticles located solely at the pore end(detailed below). In this inorganic architecture, PE chains must enterand diffuse to fill the pore length to access the Pt active sites.Platinum nanoparticles were chosen as catalytic entities because oftheir established performance in catalytic hydrogenolysis ofcarbon-carbon bonds in small hydrocarbons and recently in HDPE.

The porous catalyst was synthesized by loading 3.2±0.5 nm-diameter Ptnanoparticles onto amine-functionalized silica spheres (diameter ˜127±7nm) and then growing a 110±8 nm thick shell of mesoporous silica (mSiO₂)with 2.4±0.2 nm-diameter pores organized radially from the silicasphere. The pore length is equal to the thickness of the mSiO₂ shell, asdisplayed by the transmission electron microscopy (TEM) image (see FIG.4 a ). This three-layered spherical shell-type construction(mSiO₂/Pt/SiO₂) places the Pt nanoparticles at the terminal end oflinear channels (i.e., at the bottom of wells); this architecture and Ptnanoparticle localization is supported by the high-angle annulardark-field scanning transmission electron microscopy (HAADF-STEM) image(FIG. 4 b ). Pt nanoparticles supported on silica spheres (Pt/SiO₂, FIG.9 b ) without a mSiO₂ shell serve as a control catalyst, on which HDPEchains could be randomly adsorbed and cleaved.

Hydrogenolysis reactions using these two catalysts at ca. 0.001 Pt wt %loading (corresponding to a very small amount of reactive species, 1 mgPt in 100 g HDPE) were then performed solvent-free with ca. 3 g HDPE and200 psi H₂ at 250° C. as standard conditions. The products and theirdistribution were analyzed by gas chromatography (GC) and HT-GPC, which,taken together, give an accurate representation of the hydrocarbondistribution from low molecular mass to high molecular mass. HT-GPCanalysis of the residual polymeric materials, before and afterextraction of species with carbon numbers C_(n)<40, distinguishes theperformance of the porous and nonporous catalytic architectures (FIG. 5a,b ). Next, the yield and composition of species in the headspace ofthe pressurized reactor and of the isolated oils were analyzedindividually, and then the data from the two phases were combined togive the representative mass-weighted distribution, normalized toaccount for yields of the two phases, of low molecular mass carbonnumbers (to C₃₅, FIG. 5 c ). Comparing the populations of hydrocarbonspecies obtained from hydrogenolysis of HDPE using the mSiO₂/Pt/SiO₂catalyst to those obtained from nonporous Pt/SiO₂ catalyst revealsseveral characteristic features of processive behavior in the formercatalyst. Specifically, products afforded by the processive, porouscatalyst show (1) identical molecular mass properties of bulk HDPEbefore and after catalytic hydrogenolysis, (2) a narrower distributionof small molecule carbon numbers that is independent of Pt-catalyzedconversion, and (3) few detectable species with intermediate molecularmasses in between those of the produced fragments and the residualpolymer.

FIG. 5 shows (a) Combined table of HT-GPC and GC data showing narrowconversion-independent product distributions from mSiO₂/Pt/SiO₂ andbroader, conversion-dependent product distributions obtained withPt/SiO₂. The data is presented as pairs of analyses for each experiment,before and after extraction with methylene chloride. The HT-GPC data ofall condensed-phase organic materials, prior to extraction withmethylene chloride, reveals a substantial decrease in M_(a) and increasein D for both catalytic architectures. (b) HT-GPC analysis of molecularmass and distributions of HDPE (black), HDPE after hydrogenolysis usingmSiO₂/Pt/SiO₂, and HDPE after hydrogenolysis using Pt/SiO₂ for 24 h,showing equivalent bulk polymer properties after catalysis using theporous catalyst and change in the bulk HDPE after hydrogenolysis by thenonporous catalyst. (c) Combined distributions of the gas and liquidproducts (weighted by % yield of the products in the two phases)obtained from the hydrogenolysis of HDPE using mSiO₂/Pt/SiO₂ (top) andPt/SiO₂ (bottom) after 6 h at 250° C. under 200 psi of H₂.

First, hydrogenolysis of HDPE using Pt/SiO₂ results in a significanttransformation of M_(n) and dispersity D (M_(w)/M_(n)) of thepolyethylene fraction, whereas the comparable mSiO₂/Pt/SiO₂-catalyzedhydrogenolysis provides equivalent molecular mass properties to those ofthe starting HDPE (see FIGS. 5 a and b ) as expected for a processiveprocess. Using the 24 h experiment under standard conditions as arepresentative example, hydrogenolysis of HDPE employing mSiO₂/Pt/SiO₂as the catalyst (0.0013 Pt wt %) provides condensed-phase organicmaterials; analysis of this crude mixture by HT-GPC reveals asubstantial decrease in M_(n) and increase in D compared to untreatedHDPE. Extraction of all soluble low molecular mass species (7.2%) fromthe crude reaction mixture with refluxing dichloromethane gives residualinsoluble HDPE (M_(n)=6.8 kDa and Ð=4.7) with equivalent properties tothose of the unreacted, dichloromethane-washed HDPE starting material(M_(n)=6.6 kDa and Ð=4.6). Likewise, hydrogenolysis using themSiO₂/Pt/SiO₂ catalyst for 6 h (6.7% conversion) and 48 h (25%conversion) afford residual HDPE with similar M_(n) and D values. Thatis, the bulk properties of the HDPE are largely unchanged duringhydrogenolysis with mSiO₂/Pt/SiO₂, even as the HDPE is consumed andsmall molecular mass species are produced.

Reactions of HDPE and H₂ with the nonporous Pt/SiO₂ catalyst underequivalent standard conditions (0.0013 Pt wt %) also result inhydrogenolysis (20.3% conversion after 24 h). The HT-GPC data revealsthat residual HPDE is significantly transformed even after extractionwith CH₂Cl₂, highlighting the contrasting behavior of Pt/SiO₂ andmSiO₂/Pt/SiO₂. In particular, the molecular mass of the insolublepolymeric material is reduced (M_(n)=3.7 kDa) and the dispersity(Ð=11.7) is considerably broadened from the values of both the virginand unreacted/dichloromethane-washed polyethylene starting materials.Moreover, characteristics of the polymer are altered as a function ofthe extent of conversion. For example, the dispersity decreases withhigher conversion as a result of a larger fraction of highest molecularmass species undergoing cleavage, whereas at lower conversion, the HDPEproperties are not distinguished outside of error from startingmaterials. Catalyst-free thermal treatment of HDPE under H₂ also resultsin polymer with lower M_(n), before and after washing with methylenechloride.

Second, the carbon number distribution of molecular species produced bymSiO₂/Pt/SiO₂ gives the appearance of a bell-like distribution, centeredat C₁₂-C₁₆ numbered chains that comprise ca. 40% of the hydrocarbonspresent after 10% conversion (see FIG. 5 c ). The higher molecular massspecies from C₂₆-C₃₆ (above which each C_(n) species is less than 0.01%)are only 2% of the observed products. This C₁₄-centered bell-likedistribution, measured at low conversion, represents the intrinsicselectivity of the catalyst. Remarkably, this Pt-hydrogenolysis produceddistribution is also largely independent of the conversion level from˜5% up to 25%, although the relative quantity of the lowest and highestmolecular mass species varies somewhat. These species are attributed,which appear outside of the normal distribution in the samples, tobackground reactions because they are the predominant products incontrol reactions using Pt-free mSiO₂/SiO₂ material (i.e., acidcatalyzed) or in the absence of any inorganic additive. A 17 kDa (Ð=1.1)polyethylene was also tested in this mSiO₂/Pt/SiO₂-catalyzedhydrogenolysis, which also produced a bell-like distribution of chainlengths. Finally, quantitative conversion of the HDPE to gaseous anddichloromethane-soluble species was observed after 5.5 d at 250° C., andfor that experiment ca. 4-fold higher catalyst loading (albeit still lowat 0.0039 Pt wt %) gave 57% isolated oils. The carbon numberdistribution again centers around low molecular mass species (C₉-C₁₅ isca. 55%). At this long reaction time, it is likely that smallermolecular mass hydrocarbons also undergo hydrogenolysis steps.

In contrast, the hydrocarbon chains obtained from Pt/SiO₂ appeared as aflattened distribution of species with carbon numbers from Cis to C₂₆(5.8±0.2% for each species after ca. 20% conversion). In addition, thehigher range, C₂₆-C₃₆ is significant at ca. ˜17% of the distribution.Note that HT-GPC results indicate that the higher molecular mass speciesproduced by Pt/SiO₂ are more abundant than indicated by GC data in FIG.5 c due to their lower solubility. As such, the GC analysis onlydescribes the lower end of a much broader distribution. Nonetheless, itis clear that the C_(n) distribution is sensitive to the extent ofreaction with the nonporous Pt/SiO₂ as hydrogenolysis catalyst. After 48h (27% conversion), for example, each individual C_(n) species is lessthan 4.5% of the sample, and the majority species range all the way fromC₁₃ to C₃₀. Additional control experiments employing porous supports forPt, namely Pt/mSiO₂ (mSiO₂=MCM-41 or SBA-15) which lack theshell/site/core architecture, are active for HDPE hydrogenolysis at 250°C., but Pt/MCM-41 gives a broad distribution of hydrocarbon productsrather than processive-like selectivity, while Pt/SBA-15 affords a wide,distribution flattened from C₁₈-C₂₃. A conventional hydrocrackingcatalyst NiMo/γ-Al₂O₃ also gives a broad distribution of hydrogenolysisproducts.

Finally, the entire distribution of hydrocarbon products frommSiO₂/Pt/SiO₂-catalyzed hydrogenolysis contains only low molecular masshydrocarbons (mainly from C₁₂ to ca. C₁₈) and the original HDPE chains,while hydrocarbon fragments resulting from partial deconstruction ofHDPE chains are not present in significant quantities. This result isinferred from a composite analysis of the GC-MS and HT-GPC data,comparing results for the two catalyst architectures before and afterextraction with methylene chloride. In particular, the polymericmaterials produced by hydrogenolysis with the random Pt/SiO₂ catalystcontain significant quantities of insoluble, lower molecular massspecies not present in the starting polymer, as revealed by the changein M_(n) values which are sensitive to low molecular mass species in thepopulation. In contrast, new species in this intermediate molecular massrange are not present in reactions using the mSiO₂/Pt/SiO₂ catalystbecause they are not found in the low molecular mass fraction (from GCanalysis) or in the insoluble residual polymer fraction, since molecularmass properties of CH₂Cl₂-washed polymer are equivalent before and afterreaction. This point is further supported by the distinct distributionsof lower molecular mass species obtained by GC-MS (and simulateddistillation column GC-FID), which show that the porous catalyst favorslower molecular mass products.

The contrasting results for the two catalytic architectures indicatethat, when using mSiO₂/Pt/SiO₂ as the catalyst, (1) a fraction of theHDPE chains are not affected during catalysis, (2) all conversion intosmaller hydrocarbons occurs from a subset of polyethylene chains, and(3) any transformed chain is entirely deconstructed into small,dichloromethane-soluble molecules. These results are consistent with aprocessive catalytic process, in which the polymer chains are notreleased from the catalytic pores, while small molecular mass productsare allowed to escape.

Remarkably, catalytic hydrogenolysis of HDPE at 300° C. for 24 h givesquantitative conversion to a narrow C₁₆-centered distribution ofhydrocarbon chains, with the same median as produced at 250° C. withpartial conversion. This narrow distribution indicates that the catalystalso operates through a processive mechanism at high conversion andhigher temperature, in reactions in which rates of polymer adsorptionand desorption, polymer transport within the pores, carbon-carbon bondhydrogenolysis, and product desorption have increased. Pore diameter mayalso affect rates of adsorption/desorption and diffusion processeswithout affecting hydrogenolysis rates. Impressively, mSiO₂/Pt/SiO₂catalysts with smaller (1.7 nm) diameter pores give a distributioncentered at shorter chains, and larger (3.5 nm) diameter pores affordlonger chain products (FIG. 6 ). Thus, the physical dimensions of thepores may be used to tune the median of the product distribution.

Example 4—Hydrogenolysis at 6 h Reactions at 250° C.

Conversion of HDPE (M_(n)=5.9 kDa, Ð=4.5) into soluble small moleculeswith mSiO₂/Pt/SiO₂ (0.042 Pt wt/silica wt %; 0.00087 Pt wt/HDPE wt %)was 6.7% after 6 h, determined by the sum of mass of extracted, isolatedoils and the mass of gaseous species produced (the latter was assessedby difference in mass of reaction mixture before and after catalyticreactions). Conversion is defined as:

$\begin{matrix}{{{Conversion}{of}{HDPE}} = {\left\{ {1 - \frac{{mass}{of}{residual}{HDPE}}{{initial}{mass}{of}{HDPE}}} \right\} \times 100\%}} & (4)\end{matrix}$

Conversion was slightly higher (8.0%) with the nonporous Pt/SiO₂catalyst (0.478 Pt wt/silica wt %; 0.00099 Pt wt/HDPE wt %). These lowconversion conditions are used to evaluate the intrinsic behavior of thecatalytic materials. The products were analyzed in two parts, namelyvolatile species contained in the headspace and non-volatile,extractable oils. In these experiments, the volatile species wereobtained by venting the reactor at reaction temperature (250° C.). Oilswere obtained by repeated extraction of the residual solids withmethylene chloride at 80° C. Yields of gas phase, oil phase, andresidual solid, tabulated in Table 4, are defined as:

$\begin{matrix}{{yield} = {\left\{ \frac{{mass}{of}{products}}{{initial}{mass}{of}{HDPE}} \right\} \times 100\%}} & (5)\end{matrix}$

The residual solids were analyzed by HT-GPC, and the results of thatanalysis are described above.

As a control, thermal treatment of the same HDPE under H₂ in thepresence of a silica-only material (composed of mesoporous silica-coatedsolid silica spheres, mSiO₂/SiO₂) results in only ca. 3 wt % conversionto small molecule products. In contrast to the catalytic experiments inthe presence of platinum, most observed low molecular weight speciesfrom this ‘thermal’ treatment were unsaturated (olefinic) in nature,which suggests homolytic cleavage of PE chains rather thancatalyst-mediated hydrogenolysis. These results indicate that catalystslocated at the internal terminus of a pore are active for hydrogenolysisof PE, even though a background thermal degradation of HDPE contributesto the molecular species present in the experiments.

TABLE 4 Catalytic data and mass balance of reactions performed at 250°C. for 6 h Pt Conversion Conversion loading HDPE to volatiles to liquidsSolid residue Catalyst (wt %)^(a) (g)^(b) in g (%) in g (%) in g (%)mSiO₂/ 0.00087 3.130 0.105 0.107 2.918 Pt/SiO₂ ^(c) (3.35%) (3.42%)(93.2%) Pt/SiO₂ ^(d) 0.00099 3.032 0.121 0.121 2.790 (3.99%) (3.99%)(92.0%) mSiO₂/ 0.00087 3.008 0.073 0.153 2.782 Pt/SiO₂ ^(e) (2.4%)(5.09%) (92.5%) Pt/SiO₂ ^(f) 0.0018  3.009 0.056 0.349 2.604 (1.9%)(11.6%) (86.5%) mSiO₂/ — 3.003 0.058 0.031 2.914 SiO₂ (1.93%) (1.03%)(97.0%) Thermal^(g) — 2.947 0.018 0.020 2.909 (0.61%) (0.68%) (98.7%)^(a)wt % Pt with respect to HDPE. ^(b)HDPE properties: M_(n) = 5.9 kDa,Ð = 4.5. ^(c)Pt loading on mSiO₂/Pt/SiO₂catalyst (0.042 Pt wt/silica wt%); the pressurized reaction vessel was vented and headspace was sampledat 250° C. to examine volatile species under reaction conditions. ^(d)Ptloading on Pt/SiO₂ catalyst (0.478 Pt wt/silica wt %); the pressurizedreaction vessel was vented and headspace was sampled at 250° C. toexamine volatile species under reaction conditions. ^(e)Pt loading onmSiO₂/Pt/SiO₂ catalyst (0.040 Pt wt/silica wt %); the pressurizedreaction vessel was vented and sampled at room temperature to examinevolatile species. ^(f)Pt loading on Pt/SiO₂ catalyst (0.59 Pt wt/silicawt %); reaction vessel was vented and sampled at room temperature toexamine volatile species. ^(g)The pressurized reaction vessel was ventedand the headspace was sampled at 250° C. to examine volatile species.

Gas chromatograms of the products and corresponding carbon numberdistribution from mSiO₂/Pt/SiO₂ catalyzed hydrogenolysis reactions areshown in FIGS. 24 to 26 and 31 to 34 , while those of thePt/SiO₂-catalyzed reactions are shown in FIGS. 27 to 29 and 35 to 37 ;comparisons of carbon number distribution are given in FIGS. 30 and 38 .GC and carbon number distributions for control experiments without Ptand without inorganic oxide are given in FIGS. 39 to 44 .

Example 5—Hydrogenolysis at 24 h Reactions at 250° C.

Conversion of HDPE (M_(n)=5.9 kDa, Ð=4.5) into soluble small moleculesby hydrogenolysis with mSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %; 0.0013 Ptwt/HDPE wt %; 2.4 nm diameter mesopores) was 10.3% after 24 h,determined by the sum of masses of extracted, isolated oils and the massof gaseous species produced (assessed by difference in mass of reactionmixture before and after catalytic reactions). Conversion is defined asabove in 6 h reactions. Conversion was higher (20.3%) after 24 h inhydrogenolysis reactions using the nonporous Pt/SiO₂ catalyst (1.7 Ptwt/silica wt %; 0.0013 Pt wt/HDPE wt %) under identical conditions.Similar conversions are obtained with Pt/MCM-41 compared tomSiO₂/Pt/SiO₂, while the larger pore-sized Pt/SBA-15 catalytic materialgave lower conversions. A hydrocracking catalyst NiMo/γ-Al₂O₃ also showssimilar conversion of HDPE.

Yields of gas phase, oil phase, and residual solid are tabulated inTable 5. Of the low molecular weight products obtained fromhydrogenolysis catalyzed by mSiO₂/Pt/SiO₂, 30.1% were released from theheadspace while 69.3% were oils. A smaller percentage of the productsfrom Pt/SiO₂-catalyzed hydrogenolysis were released from the headspace(21.5%) than from the mesoporous silica-based catalyst, and a largerpercentage of oils (78.5%) were produced by Pt/SiO₂. Despite the similarpores sizes of mSiO₂/Pt/SiO₂ and Pt/MCM-41, the latter gives a broadunselective distribution. NiMo/γ-Al₂O₃ also gives a broad distributionof hydrocarbon products. That is, the mSiO₂/Pt/SiO₂ catalyst favors adistribution with lower molecular weight hydrocarbon chains. Theresidual polymeric materials that were not extracted into methylenechloride were analyzed by HT-GPC (described above).

TABLE 5 Catalytic data and mass balance of reactions performed for 24 hat 250° C. Pt loading HDPE Yield of Yield of Solid Catalyst (wt %)^(a)(g)^(b) volatiles (g) liquids (g) residue (g) mSiO₂/Pt/SiO₂ ^(c) 0.00133.024  0.096 (3.17%) 0.217 (7.18%) 2.711 (89.7%) Pt/SiO₂ ^(d) 0.00133.001  0.131 (4.37%) 0.478 (15.9%) 2.392 (79.7%) mSiO₂/Pt/SiO₂ ^(e)0.0021  0.503^(f) 0.012 (2.4%) 0.081 (16.1%) 0.410 (81.5%) mSiO₂/Pt/SiO₂^(g) 0.00087 2.999 0.157 (5.2%) 0.385 (12.8%) 2.457 (81.9%) Pt/SiO₂ ^(h)0.00087 3.008 0.271 (9.0%) 0.487 (16.2%) 2.250 (74.8%) Pt/MCM-41^(i)0.0008 3.023 0.081 (2.7%) 0.420 (13.9%) 2.522 (83.4%) Pt/SBA-15^(j)0.0008 3.037 0.038 (1.2%) 0.195 (6.4%)  2.804 (92.4%) NiMo/Al₂O₃ 98.8 mg3.059 0.057 (1.9%) 0.360 (11.8%) 2.642 (86.3%) mSiO₂/SiO₂ ^(k) n.a.2.964 0.098 (3.3%) 0.072 (2.5%)  2.794 (94.3%) ^(a)Pt wt/HDPE %. Thereaction vessels were vented and sampled at room temperature to examinevolatile species. ^(b)HDPE properties: M_(n) = 5.9 kDa, Ð = 4.5 unlessotherwise specified. ^(c)mSiO₂/Pt/SiO₂ catalyst (0.06 Pt wt/silica wt%), 2.4 nm diameter mesopores. ^(d)Pt/SiO₂ catalyst (1.7 Pt wt/silica wt%). ^(e)mSiO₂/Pt/SiO₂ catalyst (0.04 Pt wt/silica wt %; 2.4 nm pores).^(f)Low polydispersity polyethylene sample from Scientific PolymerProducts (M_(n) = 15.4 kDa, Ð = 1.1). ^(g)mSiO₂/Pt/SiO₂ catalyst (0.040Pt wt/silica wt %). ^(h)Pt/SiO₂ catalyst (0.59 Pt wt/silica wt %).^(i)0.9 Pt wt/silica wt %. ^(j)0.8 Pt wt/silica wt %. ^(k)0.065 g ofmSiO₂/SiO₂.

Gas chromatograms of the products and corresponding carbon numberdistribution from mSiO₂/Pt/SiO₂ catalyzed hydrogenolysis reactions areshown in FIGS. 45 to 48 and 61 to 63 . ¹H NMR and DEPT-135 ¹³C NMRspectra are shown in FIGS. 49, 50, 56, and 57 from samples produced bythe mSiO₂/Pt/SiO₂ catalyst.

Gas chromatograms of the products and corresponding carbon numberdistribution from Pt/SiO₂ catalyzed hydrogenolysis reactions are shownin FIGS. 51 to 53 . SimDist GC-FID, as a second method for analyticalseparation of hydrogenolysis oil products that highlights the broaddistribution of hydrogenolysis oil products (15.9% yield) from reactionof HDPE using Pt/SiO₂ is shown in FIG. 54 . The ¹H NMR spectrum of oilsobtained by hydrogenolysis using Pt/SiO₂ (1.7 Pt wt/silica wt %) ascatalyst are shown in FIG. 56 and the DEPT-135 NMR are shown in FIG. 57.

SimDist GC-FID, as a second method for analytical separation ofhydrogenolysis oil products that highlights the broad distribution ofhydrogenolysis oil products (15.9% yield) from reaction of HDPE usingPt/SiO₂ (Comparisons of carbon number distributions from mSiO₂/Pt/SiO₂and Pt/SiO₂ are given in FIGS. 55 and 67 for the two sets ofexperiments.

Gas chromatograms of the products and corresponding carbon numberdistribution from monodisperse polyethylene (M_(n)=15.4 kDa,

=1.1) from mSiO₂/Pt/SiO₂-catalyzed hydrogenolysis are shown in FIGS. 58to 60 .

Gas chromatograms of the products and corresponding carbon numberdistribution for the hydrogenolysis reaction of HDPE (M_(n)=5.9 kDa,

=4.5) using Pt/SiO₂ (0.59 Pt wt/silica wt %) as catalyst are shown inFIGS. 64-66 .

Gas chromatograms of the products and corresponding carbon numberdistribution from Pt/MCM-41 and Pt/SBA-15 catalyzed hydrogenolysisreactions are shown in FIGS. 68 to 70 and 71 to 73 , respectively.

Gas chromatograms of the products and corresponding carbon numberdistribution from NiMo/Al₂O₃ catalyzed hydrogenolysis reactions areshown in FIGS. 74 to 76 .

Gas chromatograms for a control experiment, without Pt, is given in FIG.77 .

Example 6—Hydrogenolysis at 48 h Reactions at 250° C.

Conversion of HDPE into soluble small molecules by hydrogenolysis withmSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %; 0.0013 Pt wt/HDPE wt %) after 48h at 250° C. under H₂ (200 psi) was 24.1% (as described above in theexperimental for 6 h reactions), determined by the sum of mass ofextracted, isolated oils and the mass of gaseous species produced(assessed by difference in mass of reaction mixture before and aftercatalytic reactions). Conversion was only slightly higher (27.5%) after48 h in hydrogenolysis reactions using the nonporous Pt/SiO₂ catalyst(1.7 Pt wt/silica wt %; 0.0013 Pt wt/HDPE wt %) under identicalconditions.

Yields of gas phase, oil phase, and residual solid are tabulated inTable 6. Of the low molecular weight products obtained fromhydrogenolysis catalyzed by mSiO₂/Pt/SiO₂, 23.4% were released from theheadspace as volatile species while 76.7% were present in the oilycondensed phase. An even smaller percentage of the products fromPt/SiO₂-catalyzed hydrogenolysis were released from the headspace(10.0%) than from the mesoporous silica-based catalyst, and acorresponding larger percentage of oils (90.0%) were formed. Thus, overthe sequence of times measured (6 h, 24 h, 48 h), the mSiO₂/Pt/SiO₂catalyst favors a distribution with lower molecular weight hydrocarbonchains compared to Pt/SiO₂. The residual polymeric materials that werenot extracted into methylene chloride were analyzed by HT-GPC (describedabove).

TABLE 6 Catalytic data and mass balance of reactions performed at 250°C. for 48 h Pt Conversion Conversion loading HDPE to to SolidCatalyst^(a) (wt %)^(b) (g)^(c) volatiles (g) liquids (g) residue (g)mSiO₂/ 0.0013  3.016 0.170 0.556 2.290 Pt/SiO₂ ^(d) (5.64%) (18.4%)(75.9%) Pt/SiO₂ ^(e) 0.0013  3.001 0.082 0.742 2.177 (2.73%) (24.7%)(73.5%) mSiO₂/ 0.00087 3.039 0.119 0.547 2.373 Pt/SiO₂ ^(f) (3.9%)(18.0%) (78.1%) Pt/SiO₂ ^(g) 0.0018  3.014 0.324 0.998 1.692 (10.7%)(33.1%) (56.1%) ^(a)The reaction vessel was vented and sampled at roomtemperature to examine volatile species. ^(b)Pt wt/HDPE wt %. ^(c)HDPEproperties: M_(n) = 5.9 kDa, Ð = 4.5. ^(d)mSiO₂/Pt/SiO₂ catalyst (0.06Pt wt/silica wt %). ^(e)Pt/SiO₂ catalyst (1.7 Pt wt/silica wt %).^(f)mSiO₂/Pt/SiO₂ catalyst (0.040 Pt wt/silica wt %). ^(g)Pt/SiO₂catalyst (0.59 Pt wt/silica wt %).

Gas chromatograms of the products and corresponding carbon numberdistribution from mSiO₂/Pt/SiO₂ catalyzed hydrogenolysis reactions areshown in FIGS. 78 to 80 , while those of the Pt/SiO₂-catalyzed reactionsare shown in FIGS. 81 to 83 ; a comparison of carbon number distributionis given in FIGS. 78-84 .

GC-MS of hydrogenolysis oil products (56.6% yield) from reaction of HDPE(M_(n)=5.9 kDa, Ð=4.5) using mSiO₂/Pt/SiO₂ (0.59 Pt wt/silica wt %) ascatalyst are shown in FIG. 85 .

Example 7—Hydrogenolysis with Quantitative Conversion at 250° C.

HDPE was converted into soluble small molecules by hydrogenolysis withmSiO₂/Pt/SiO₂ (0.06 Pt wt/silica wt %; 0.0013 Pt wt/HDPE wt %) after 136h at 250° C. under H₂ (200 psi) yielding 94% gases and oils (asdescribed above in the experimental for 6 h reactions), determined bythe sum of mass of extracted, isolated oils and the mass of gaseousspecies produced (assessed by difference in mass of reaction mixturebefore and after catalytic reactions). Yields of gas phase, oil phase,and residual solid are tabulated in Table 7.

TABLE 7 Catalytic data and mass balance of the reaction performed for136 h and 250° C. Pt Conversion Conversion Solid loading HDPE to toresidue Catalyst (wt %)^(a) (g)^(b) volatiles (g) liquids (g) (g)mSiO₂/Pt/SiO₂ ^(c) 0.0039 2.015 0.754 1.14 0.12 (37.4%) (56.6%) (6%)^(a)Pt wt/HDPE wt %. ^(b)HDPE properties: M_(n) = 5.9 kDa, Ð = 4.5.^(c)mSiO₂/Pt/SiO₂ catalyst (0.06 Pt wt/silica wt %). The reaction vesselwas vented and sampled at room temperature to examine volatile species.

Example 8—Hydrogenolysis at 300° C. for 24 h

Conversion of HDPE (M_(n)=5.9 kDa,

=4.5) into soluble small molecules by hydrogenolysis with 2.4 nm poremSiO₂/Pt/SiO₂ (0.27 Pt wt/silica wt %; 0.004 Pt wt/HDPE wt %) was 97.9%after 24 h at 300° C. under H₂ (200 psi at room temperature, 250 psi at300° C.) as described in above, determined by the sum of mass ofextracted, isolated oils and the mass of gaseous species produced(assessed by difference in mass of reaction mixture before and aftercatalytic reactions). Yields of gas phase, oil phase, and residual solidare tabulated in Table 8.

TABLE 8 Catalytic data and mass balance of the reactions performed at300° C. Pt Conversion Conversion loading HDPE to to Solid Catalyst (wt%)^(a) (g)^(b) volatiles (g)^(c) liquids (g) residue (g) 1.7 nm 0.0043.034 1.043 1.532 0.459 mSiO₂/ (34.4%) (50.5%) (15.1%) Pt/SiO₂ ^(d) 2.4nm 0.004 3.073 0.744 2.264 0.065 mSiO₂/ (24.2%) (73.7%) (2.1%) Pt/SiO₂^(e) 3.5 nm 0.004 3.027 0.651 2.320 0.056 mSiO₂/ (21.5%) (76.6%) (1.0%)Pt/SiO₂ ^(f) Pt/SiO₂ ^(g) 0.004 3.040 0.449  0.7225 1.868 (14.8%)(23.8%) (61.4%) mSiO₂/ n.a. 2.992 0.019 0.231 2.752 SiO₂ (0.64%) (7.72%)(91.6%) ^(a)Pt wt/HDPE wt %. ^(b)HDPE properties: M_(n) = 5.9 kDa, Ð =4.5. ^(c)The reaction vessel was vented and sampled at room temperatureto examine volatile species. ^(d)035 Pt wt/silica wt %. ^(e)0.27 Ptwt/silica wt %. ^(f)0.033 Pt wt/silica wt %. ^(g)2.8 Pt wt/silica %.

Gas chromatograms of the products and corresponding carbon numberdistribution from 1.7 nm diameter pore mSiO₂/Pt/SiO₂ catalyzedhydrogenolysis reactions at 300° C. for 24 h are shown in FIGS. 86 to 88, data from 2.4 nm diameter pores are shown in FIGS. 89 to 91 , and datafrom 3.5 nm diameter pores are shown in FIGS. 92 to 94 . A stack-plotcomparing GC traces of the three catalysts is giving in FIG. 95 .

Gas chromatograms of the products and corresponding carbon numberdistribution from Pt/SiO₂-catalyzed hydrogenolysis reactions at 300° C.for 24 h are shown in FIGS. 95 to 98 . Pt-free control reaction data isgiven in FIGS. 99 to 101 .

Example 9—Conversion of 50 g of HDPE at 300° C.

Over conversion of 50 g of HDPE (M_(n)=5.9 kDa,

=4.5) into soluble small molecules by hydrogenolysis occurred with 2.4nm pore mSiO₂/Pt/SiO₂ (0.27 Pt wt/silica wt %; 0.018 Pt wt/HDPE wt %)over 4 d and 16 h at 300° C. under H₂ (200 psi at room temperature, 250psi at 300° C.). Yields of gas and liquid products are given in Table 9.

TABLE 9 Catalytic data and mass balance of the reaction performed for112 h and 300° C. Pt Solid loading HDPE Conversion to Conversion toresidue Catalyst (wt %)^(a) (g)^(b) volatiles (g) liquids (g) (g) mSiO₂/0.018 50.012 33.944 (67.9%) 16.068 (32.1%) — Pt/SiO₂ ^(c) ^(a)Pt wt/HDPEwt %. ^(b)HDPE properties: M_(n) = 5.9 kDa, Ð = 4.5. ^(c)mSiO₂/Pt/SiO₂catalyst (0.27 Pt wt/silica wt %). The reaction vessel was vented andsampled at room temperature to examine volatile species.

The GC-MS trace of the sampled headspace for the thermal reaction andthe GC-MS of oil products of 50 g of HDPE (M_(n)=5.9 kDa, Ð=4.5) in thepresence of 2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.27 Pt wt/silica wt %)material (reaction time 112 hours) is show in FIGS. 102 and 103respectively.

Example 10—Post-Consumer HDPE from Grocery-Type Shopping Bags

HDPE from used grocery shopping bags (M_(n)=10.6 kDa, M_(w)=150.1 kDa,

=14.1). After use, the bags were cut into small pieces and loaded intothe glass liner of the reactor autoclave. The reactor vessel, containingthe waste HDPE was heated under vacuum at 40° C. for 12 h. The reactorwas cooled and the mSiO₂/Pt/SiO₂ catalyst was added. The reactor waspressurized with N₂ and evacuated 3×, and then it was pressurized withH₂, heated to the reaction temperature, and mixed using an overheadmechanical stirrer.

Yields of gas, liquid and solid products are given in Table 10.

TABLE 10 Catalytic data and mass balance of the reactions performed. PtConversion Conversion loading HDPE to to Solid Catalyst^(a) (wt %)^(b)(g) volatiles (g) liquids (g) residue (g) mSiO₂/ 0.0021 1.239 0.2220.251 0.766 Pt/SiO₂ ^(c) (17.9%) (20.3%) (61.8%) mSiO₂/ 0.0072 1.5040.160 0.502 0.842 Pt/SiO₂ ^(d) (10.6%) (33.4%) (56.0%) ^(a)2.4 nmdiameter pore mSiO₂/Pt/SiO₂ catalyst (0.04 Pt wt/silica wt %). ^(b)Ptwt/HDPE wt %. The reaction vessel was vented and sampled at roomtemperature to examine volatile species. ^(c)48 h reaction at 250° C.^(d)24 h reaction at 300° C.

Gas chromatograms of the products from the catalytic reaction at 250° C.for 48 h are shown in FIGS. 104 and 105 .

Gas chromatograms of the products from the catalytic reaction at 300° C.for 24 h are shown in FIGS. 106 and 107 .

Example 11—Catalytic Hydrogenolysis of Isotactic Polypropylene

Conversion of iPP into soluble small molecules by hydrogenolysis with2.4 nm diameter pore mSiO₂/Pt/SiO₂ (0.0008 Pt wt/silica wt %; 0.04 Ptwt/iPP wt %) after 24 h at 300° C. under H₂ (200 psi at roomtemperature, 250 psi at 300° C.) was 78.9% (as described above in theexample for 6 h reactions), determined by the sum of mass of extracted,isolated oils and the mass of gaseous species produced (assessed bydifference in mass of reaction mixture before and after catalyticreactions).

Yields of gas phase, oil phase, and residual solid are tabulated inTable 11.

TABLE 11 Catalytic data and mass balance of the iPP hydrogenolysisreaction at 300° C. Pt Conversion Conversion Solid loading HDPE to toresidue Catalyst (wt %)^(a) (g) volatiles (g) liquids (g) (g)mSiO₂/Pt/SiO₂ ^(b) 0.0008 3.094 0.651 2.443 0.002 (21.0%) (78.9%)Pt/SiO₂ 0.0008 3.054 1.443 1.611 — (47.2%) (52.8%) ^(a)Pt wt/HDPE wt %.The reaction vessel was vented and sampled at room temperature toexamine volatile species. ^(b)mSiO₂/Pt/SiO₂ catalyst (0.04 Pt wt/silicawt %, 2.4 nm diameter pore). ^(c)2.3 Pt wt/silica wt %.

The GC-MS trace of the sampled headspace and the GC-MS of oil productsfor the hydrogenolysis reaction of iPP using 2.4 nm diameter poremSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %) as catalyst (reaction time 112hours) is show in FIGS. 108 and 109 respectively.

The GC-MS trace of the sampled headspace and the GC-MS of oil productsfor the hydrogenolysis reaction of iPP using 2.4 nm diameter poremSiO₂/Pt/SiO₂ (0.04 Pt wt/silica wt %) as catalyst (reaction time 24hours) is show in FIGS. 110 and 111 respectively.

Example 12—Dynamics of Polyethylene in Silica Materials

The interactions between silica and HDPE are characterized by ¹³Csolid-state nuclear magnetic resonance (SSNMR) spectroscopy, whichinform upon both the conformation and dynamics of polyethylene adsorbedon a support. Briefly, the γ-gauche effect enables the identification ofanti (linear, zig-zag, 32 ppm), gauche (bending, 27 ppm), and mobile(˜29 ppm) conformers by their ¹³C NMR chemical shift. This approach has,for example, been used to detect the ordering of alkyl chains onsurfaces, as well as to observe chain diffusion in bulk polyethylene.Also, note that polydimethoxysilane and polyethylene oxide were shown tothread into zeolite or metal-organic frameworks (MOF) pores,respectively. A priori, one might conjecture that theseoxygen-containing polymers form stronger interactions with solidmaterials than polyethylene, especially because the oxygen-freepolyvinylidene fluoride did not readily enter the pores of the MOF.

Monolayers of ¹³C-enriched polyethylene (*PE,) with a number-averagemolecular mass (M_(n)) of 130 kDa (extended chain length of ˜1 μm) wereintroduced onto Davisil silica gel or mesoporous silica nanoparticles(mSiO₂) with an average particle diameter of 450 nm featuring 1.5nm-wide, ca. 200 nm long pores organized radially from the center of theparticle. The ¹³C magic-angle-spinning (MAS) SSNMR spectrum obtained forthe *PE/Davisil revealed anti, mobile, and gauche conformers similar tothat obtained by Inoue, D., et. al., “Structural and Dynamical Studiesof ¹³C-Labeled Polyethylene Adsorbed on the Surface of Silica Gel byHigh-Resolution Solid-State ¹³C NMR Spectroscopy,” Acta. Polymer. 46,420-423 (1995), which is hereby incorporated by reference). Remarkably,the ¹³C MAS SSNMR spectrum of *PE/mSiO₂ features signals of only antiand mobile conformers (FIG. 2 ). The prominence of the anti-conformer,compared to the gauche, in *PE/mSiO₂ would suggest that the mesoporousmaterial is able to induce the formation of long, zig-zag PE domains,consistent with the polymer being threaded into the linear channels ofthe mSiO₂. Prior work suggests that the mobile peak originates from PEchains situated away from the material surface (i.e., located outside ofthe pore).

Several additional experiments further supported these assignments.First, the integrated intensity of the anti and mobile resonances (1:4),obtained by deconvolution of the spectrum in FIG. 2 b , matched theestimated percentage (20%) of ca. 1 m-long polymer chains that couldenter roughly 200 nm long pores. Second, cross-polarization (CP) andJ-mediated Incredible Natural Abundance DoublE QUAntum TransferExperiment (INADEQUATE) experiments revealed separate domains composedof anti and mobile methylene units, and the former domain was rigid andextended. Finally, shorter chain HDPE (M_(n)=7 kDa, ¹³C at naturalabundance) loaded onto the mSiO₂ provided a spectrum that exclusivelyfeatured a single sharp resonance with the chemical shift of theanti-conformer (FIG. 2 c ). Importantly, this result confirmed thesuspected spectral distinction of intra- and extra-pore polymer.Additional experiments employing spherical silica particles and a seriesof surface modifications, confirm that the topology of the material isdirecting the conformation of the polymer. Taken together, the data leadto the conclusion that HDPE chains thread the mouths of 1.5 nm diameterpores in mSiO₂, insert a portion of the chain length that matches thelength of the pore, and adopt an extended conformation templated by thelinear pore.

These intra- and extra-pore polymer assignments in combination with 2Dexchange spectroscopy (EXSY), as demonstrated by Schmidt-Rohr, et. al.,“Chain Diffusion between Crystallized and Amorphous Regions inPolyethylene Detected by 2D Exchange ¹³C NMR,” Macromol. 24, 5288-5293.(1991), which is hereby incorporated by reference in its entirety),allow detailed interrogation of the dynamic behavior of the species inthis system. In EXSY experiments, two time evolution periods areseparated by a mixing time (t_(mix)) during which the molecules are freeto diffuse. Chain diffusion creates off-diagonal cross-peaks in thespectrum wherein a given carbon is found inside the pore for the firstevolution period, and outside for the second, for instance. Diffusioncross-peaks were easily identified (top-left and bottom-right corners ofthe black square) in a representative ¹³C EXSY spectrum (FIG. 3 a ).Interestingly, the cross-peak corresponded to exchange between theinner-pore region and a small, higher chemical shift shoulder of themobile resonance, rather than exchange directly between rigid and mobiledomains. This higher chemical shift signal was assigned to methylenegroups located near the mouth of the pore because the higher shiftindicates the species has slightly higher probability of adopting theanti-conformation than in the mobile domain. This environment isanalogous to the interfacial region present in between the amorphous andcrystalline regions of bulk polyethylene.

The ¹³C EXSY experiment was repeated for t_(mix) values of up to 4 s attemperatures from 72 to 114° C. to estimate the kinetics andthermodynamics of the chain diffusion through the channel.Interestingly, it was observed that the cross-peak intensities did notconverge to those expected from pure statistical exchange but thatinstead a very significant fraction, ca. 70%, of the intra-pore polymernever exits the pore, even at 114° C. (the intensities plotted in FIG. 3b can be read as fractions of intra-pore polymer that can freely leavethe pore). As expected, the fraction of the polyethylene that can freelyescape the silica channel increases with temperature. Importantly,however, this result demonstrates that the material itself never fullyreleases the polymer chain. An estimation of equilibrium behavior basedon these data suggests that a significant fraction of *PE remainsadsorbed in pores at catalytically-relevant temperatures. In addition,experiments performed on eicosane (C₂₀H₄₂) show that lower molecularmass fragments do not adsorb strongly onto silica or into 1.5 nm pores.That is, the numerous cumulative dispersion interactions between poreand long hydrocarbon polymer result in strong binding, whereas fewerinteractions with small molecules should allow relatively efficientrelease. Together, this behavior provides the properties required tomimic the processive enzymatic polymer deconstruction process forpolymer upcycling depicted in FIG. 1 b.

The polymer must also be able to thread through the pore at a reasonablerate for efficient processive catalysis. To probe this translocationrate, a relationship between the cross-peak intensities (1) and thediffusion length (L=rI=√{square root over (D_(eff)t_(mix))}) wasexploited to extract effective intra-pore diffusion coefficients(D_(eff)); where r is the pore length (200 nm). The diffusioncoefficient depends on the mixing time (FIG. 3 c ), due to the bindingof the polymer, but the initial diffusion coefficient, corresponding tothe rate when the polymer is closest to its equilibrium position, iswithin experimental error with the diffusion coefficient of PE in themelt. Similarly the activation energy for the translation through thepore (80±24 kJ/mol, FIG. 3 d ) agrees with that measured in bulk PE,These results, therefore, show that while the silica pore is able tobind to PE, this binding is not so strong as to prevent short-rangediffusion of the polymer. EXSY experiments performed using the catalyticarchitecture discussed in the next section show the same behavior.

Example 13—Polyethylene-Surface Interactions

Solid-State NMR

To confirm that the resonance at 32 ppm indeed corresponds to a rigidand more extended polyethylene conformer we have performed ¹H-¹³Ccross-polarization (CP)MAS as well as a J-mediated Incredible NaturalAbundance DoublE QUAntum Transfer Experiment (INADEQUATE). Inconsideration of the fact that a threaded polymer should exhibit muchlower molecular mobility, and since the CP transfers are mediated by¹H-¹³C dipolar couplings, which in turn are weakened by molecularmotions, the mobile part of polymer will be underrepresented in theresulting CPMAS spectrum when compared to the quantitative ¹³C MASspectrum shown in FIG. 2 in the main text. Indeed, the relative peakintensities in the spectrum shown in FIG. 112 (top) clearly confirm thehigh mobility of polyethylene fragments resonating at 29 ppm.

The INADEQUATE experiment returns a non-zero intensity for all ¹³C siteshaving non-magnetically-equivalent ¹³C neighbors. As such, while acorrelation within the all-anti domain is expected (since homonuclear¹³C-¹³C dipolar coupling prevents magnetic equivalence), a mobile-mobilecorrelation is not, since this site is homogeneously-broadened andliquid-like, as evidenced by its narrowing at elevated temperatures andinefficient cross-polarization. A correlation between both resonanceswould result in a non-zero intensity at 29 ppm. In this experiment, onlythe signal from the anti conformer survived the double quantum filter,demonstrating that indeed the two resonances belong to separate domainsand that there are indeed long, all anti, polyethylene segments when thepolymer is loaded onto this material (FIG. 112 ).

To substantiate the inventor's theory that the textural properties ofthe material are what is controlling the polymer's folding twoadditional control experiments were performed. The first of these wasgauged at determining whether the surface chemistry (functionalgroup/OH, densities) could also influence the folding of the polymer. Tothis aim, the mesoporous silica material was partly dehydroxylated,which was found to linearly-orient the polymer molecules, and repeatedthe ¹³C MAS NMR experiment, following the polymer loading and washingprocedure outlined above. The obtained spectrum was essentiallyidentical to that obtained with the relatively wet surface (see FIG. 113) with the exception that the signal amplitudes were decreased by afactor of 38. This indicates that the polymer-surface interactions mustbe weaker in the dehydroxylated material, vide infra, and hence more ofit was washed away by the solvent, but otherwise the conformation of thepolymer at the material surface is unaffected by this change.

Secondly, the results obtained from the polymer on the mSiO₂ werecompared with that obtained on a comparable material, albeit without thepores. As such, non-porous silica spheres of a comparable diameter asthe mSiO₂ (200 nm) as well as spheres of a smaller diameter (50 nm) wereprepared. The spectra acquired with the use of CP as well as Bloch decayare shown in FIG. 114 . The CP spectra emphasize the more rigid parts ofthe polymer. As can be seen, the ¹³C MAS NMR spectra for the mSiO₂ and200 nm spheres are strikingly different, evidencing that the polymer isentering the pores of the mSiO₂. Aside from that, less polymer wasloaded onto the silica spheres, as expected, due to their reducedsurface areas, and since this polymer was now able to access the longerexternal surfaces, it was considerably more rigid. In the case of thesmaller spheres (50 nm), the diameter was too small to support longcumulative polymer-surface contacts and the polymer loading wasdrastically reduced. The remaining polymer was then also far more mobilethan in the case of the 200 nm spheres.

Thirdly, to determine whether the mSiO₂ material would release showchain alkanes following a hydrolysis reaction the conformation ofeicosane in the mesoporous silica material was studied. Here eicosanewas simply melted into the mSiO₂ material in situ in the NMR rotor whichcontained an excess of the mSiO₂. Performing this experiment withpolyethylene yields a resonance at 32 ppm, as shown in the main text.With eicosane, however, even at 45° C. (it's melting point is around 37°C.) no rigid signals were observed (see FIG. 115 ), indicating that theshort oligomer is free and does not adsorb strongly to the silicasurface.

Finally, to confirm the generality of the observations made on the mSiO₂material as well as the principles' transferability to the mSiO₂/Pt/SiO₂material, ¹³C-PE was loaded onto a Pt-free core-shell material which wasthen investigated using ¹³C EXSY at a temperature of 72° C. The exchangespectra are shown in FIG. 116 below for mixing times of 0 and 1 s whereno cross-peaks are expected as well as where the cross-peak amplitudeswere expected to saturate. Vertical slices taken along the 32 ppm axisare also shown. The cross-peak saturates to a level of 0.3 correspondingto translocations of up to 30 nm, in good agreement with that measuredfor the mSiO₂ material which possessed longer pores. This resultdemonstrates that the processive behavior observed for mSiO₂ is ageneral feature that is also present in the material used for catalysis.

Analysis of the EXSY Data

EXSY data were processed using TopSpin 4.0.4. For all spectra, theregion of the F2 axis spanning 31 ppm to 34 ppm was summed, and theresulting projection was fit using one or two pseudo-Voigt functions.For spectra collected at a given temperature, the region correspondingto the pore interior was initially fit using the zero mixing timespectrum (which should have no exchange peak). The peak position andbreadth were then constrained and used in the fit of spectra with longermixing times. In addition to the function fitting the pore interior, asecond function was used to fit the interfacial region assigned topolymer at the pore mouth. The parameters of this function were allowedto vary freely and were checked for consistency between spectra withdifferent mixing times. The peak position and breadth were found to beconsistent within the resolution limit of the F1 axis (approx. 0.2 ppm).For the 72° C. spectra, artifacts arising from the truncation of themobile peak lead to spurious intensity in the interfacial region. Thisintensity was accounted for via fitting the 0 s mixing time spectra andsubtracting the intensity from spectra with non-zero mixing times.Representative spectra are presented in FIG. 117 .

Uncertainties in the parameters of the functions making up the fit, andhence the uncertainties in the ratio of the peaks, were estimated viaMonte Carlo modeling. Spectra were fit using DMfit version 20150521.These data were used to calculate Arrhenius activation energies forintra-pore diffusion (FIG. 118 ).

Example 14—Pt Nanoparticle Size

General Procedure

24 nm Stöber Silica. L-arginine (18.2 mg) and ultrapure water (13.9 mL)were thoroughly mixed. Cyclohexane (0.9 mL) was added gently to form atwo-layer system. The solution was heated to 60° C. for 30 min withstirring at ˜300 rpm. TEOS (1.10 mL) was added to the mixture, which wasthen heated at 60° C. for 20 h. After this time, the aqueous layer(bottom) was separated from the organic layer and stored in arefrigerator.

45 nm Stöber Silica. The suspension of 24 nm Stöber silica seedparticles (4 mL) was diluted with ultrapure water (14.4 mL). Cyclohexane(2 mL) was then added gently to form a two-layer system. The mixture washeated to 60° C. for 30 min with stirring at ˜300 rpm. TEOS (1.408 mL)was then quickly added, in a single portion, to the top layer, and thereaction mixture was heated at 60° C. for 30 h. After this time, thebottom layer was separated from the organic layer and stored in arefrigerator.

120 nm Stöber Silica. 120 nm SiO₂ spheres were prepared using the Stöbermethod. The above aqueous solution of 45 nm Stöber silica seed particles(1 mL) was mixed with ultrapure water (2.6 mL), ethanol (18 mL), andammonium hydroxide (1.7 mL). The mixture was stirred at 500 rpm for 1 hat room temperature. Three portions of TEOS (1.5 mL total volume) wereadded in a dropwise fashion to the solution every 30 min (0.5 mL peraddition). The reaction was stirred at room temperature for 6 h. TheSiO₂ spheres were separated, washed with an ethanol/water solution(50/50 v/v; 5×20 mL), and then dried under vacuum at room temperature.

1.7 nm Pt NPs. NaOH (12.5 mL, 0.5 M) in ethylene glycol was added to asolution of H₂PtCl₆·6H₂O (0.25 g, 0.48 mmol) in 12.5 mL of ethyleneglycol. The mixture was heated at 160° C. for 3 h accompanied by N₂bubbling. A 6-mL aliquot of the resulting solution was transferred to avial. The particles were precipitated by adding HCl (1 mL, 2 M), anddispersed in ethanol containing polyvinylpyrrolidone (PVP-K30,M_(w)=40,000, 12.2 mg). The solvent was evaporated, and the residue wasredispersed in water.

2.9 nm Pt NPs. PVP-K30 (M_(w)=40,000; 133 mg) was dissolved in anaqueous solution of H₂PtCl₆·6H₂O (20 mL, 6 mM) and methanol (180 mL).The mixture was heated at reflux (80° C.) for 3 h. The solvent wasevaporated, and the residue was redispersed in water.

5 nm Pt NPs. K₂PtCl₄ (41.5 mg), C₁₄TAB (505 mg), and PVP-K30(M_(w)=40,000; 222 mg) were added to ethylene glycol (20 mL). The vesselwas purged with argon to create an inert atmosphere, and the solutionwas heated at 140° C. for 2 h. Acetone (180 mL) was added to precipitate“as prepared” Pt NPs. The precipitate was further washed with anethanol/hexanes mixture (1/4 v/v; 5×20 mL), and ethanol (20 mL) wasadded to the material for storage.

NH₂—SiO₂. In a typical synthesis, 120 nm SiO₂ spheres (1 g) weredispersed in isopropanol (175 mL). A solution of APTS (200 μL) inisopropanol (25 mL) was added to this dispersion to functionalize thesilica spheres with NH₂ groups. The reaction mixture was allowed to ageat 80° C., and then the SiO₂ spheres were washed with ethanol (3×20 mL)and separated by centrifugation at 8000 rpm. The NH₂—SiO₂ spheres weredried under vacuum at room temperature and annealed at 100° C. in airfor 5 h.

Pt—X/SiO₂. Typically, 600 mg NH₂—SiO₂ spheres were dispersed in ethanol(180 mL). Pt NPs solution was taken out according to the desired loadingand diluted to a final volume of 220 mL with ethanol. The 220 mL dilutedPt NPs solution was added to 180 mL NH₂—SiO₂ suspension dropwise withvigorous magnetic stirring (500 rpm). After addition, the resultingPt—X/SiO₂ suspension was further sonicated for 30 min. After separation,the Pt—X/SiO₂ precipitate was washed with ethanol 5 times and stored inethanol.

MSiO₂/Pt—X/SiO₂. Pt/SiO₂ spheres (25 mg) were dispersed in ethanol (10mL) by sonication for 30 min at room temperature. A pre-mixed solutionof C₁₆TAB (165 mg) in H₂O (50 mL) and ethanol (16.3 mL) was added to theabove Pt/SiO₂ dispersion, and the mixture was sonicated for another 30min. We then added ammonium hydroxide (550 uL) to the suspension. After30 min of gentle stirring, a solution of TEOS (720 μL) in ethanol (5 mL)was added in a dropwise manner in portions (4×180 μL) every 30 min tothe above suspension. The suspension was stirred for 6 h at roomtemperature. The mSiO₂/Pt—X/SiO₂ particles were separated on acentrifuge, washed with ethanol (3×20 mL), and finally dispersed into amixture of methanol (15 mL) and concentrated hydrochloric acid (1 mL).This mixture was heated at reflux (80° C.) for 24 h to remove the C₁₆TABsurfactant. After refluxing, mSiO₂/Pt—X/SiO₂ catalysts were washedthoroughly with ethanol (6×15 mL) by centrifugation at 8000 rpm.

N₂ physisorption data for mSiO₂/Pt—X/SiO₂ catalysts is shown in table12.

TABLE 12 BET surface pore volume BJH pore TEM sizes sample area (m²/g)(cm³/g) size-ad(nm) (nm) mSiO₂/Pt-1.7/SiO₂ 981 0.81 2.4 348 (15)mSiO₂/Pt-2.9/SiO₂ 969 0.81 2.4 350 (15) mSiO₂/Pt-5.0/SiO₂ 943 0.83 2.4350 (15)

The HT-GPC analysis of molecular mass and distributions of PE (AlfaAesar 041321) is shown in FIG. 190 .

Methods and Conditions for Catalytic Reactions

Ethylene hydrogenation. Ethylene hydrogenation experiments wereconducted in a gas flow reactor. Typically, catalysts were mixed withquartz sand (200 mg). The reaction gases were composed of He (flowing at156 mL/min; 99.999%), C₂H₄ (2.4 mL/min; 99.9%), and H₂ (24 mL/min;99.995%) at 1 atm. Catalysts were preactivated in the reactor by heatingat 200° C. while flowing 10% 02/He for 1 h, He for 0.5 h, and then 10%H₂/He for 1 h. A cooling bath was used to maintain catalyst bedding at20° C. The gas composition was monitored online using an HP 5890 gaschromatography equipped with a capillary column (HP PLOT Q, 30 m×0.32mm×0.25 μm) with a flame ionization detector (FID). The ethylenehydrogenation activity was assessed using the rate at the initialportion of the reaction. The Pt NPs catalysts undergo deactivationsduring the hydrogenation reaction at rates that are related to particlesize.

Polyethylene hydrogenolysis. Polyethylene hydrogenolysis experimentswere performed in Parr autoclaves equipped with an overhead mechanicalstirrer. Polyethylene (3.0 g) and the catalyst were loaded into aglass-lined autoclave, which was sealed and purged using alternatingvacuum and argon cycles (3×). The reactor was pressurized with H₂,mixing was initiated, and the vessel heated at 300° C. for a preset time(6, 8, 12, 15 or 20 h). Then, the reactor was allowed to cool, and theheadspace was sampled and analyzed using a GC-FID. Methylene chloridewas added to the reactor, which was sealed and heated to 80° C. Theresulting suspension was filtered, and ethylene chloride was evaporatedfrom the filtrate to provide the extracted wax product. The remainingsolid on the filter was dried, its mass was determined. The yield ofgases was calculated by subtracting the initial mass of the polymer bythe mass of extracted waxes and solid residue. The extracted wax wasanalyzed using GC-MS.

Comparisons between catalytic materials. The mass of Pt used incatalytic PE hydrogenolysis experiments is normalized to give equivalentconversion to that of mSiO₂/Pt-5.0/SiO₂-catalyzed hydrogenation ofethylene under equivalent conditions.

${{{mass}({reference}) \times {activity}({reference}) \times {{wt}.\%}{Pt}({reference})} = {{mass}({catalyst}) \times {activity}({catalyst}) \times {{wt}.\%}{Pt}({catalyst})}}{{{mass}({catalyst})} = \frac{{mass}({reference}) \times {activity}({reference}) \times {{wt}.\%}{Pt}({reference})}{{activity}({catalyst}) \times {{wt}.\%}{Pt}({catalyst})}}{{reference} = {{{m{SiO}}_{2}/{Pt}} - {5./{SiO}_{2}}}}{{{mass}({reference})} = {{0.36g{{m{SiO}}_{2}/{Pt}}} - {{5./{SiO}_{2}}{used}{in}{HDPE}{hydrogenolysis}}}}{{{activity}({reference})} = {{{{initial}{experimental}{rate}{of}C_{2}H_{6}{formation}{using}{{m{SiO}}_{2}/{Pt}}} - {5./{SiO}_{2}}} = {20.5{mmol}C_{2}{H_{6} \cdot g_{Pt}^{- 1}}s^{- 1}}}}{{{{wt}.\%}{Pt}({reference})} = {\frac{{mass}{Pt}}{{{mass}{m{SiO}}_{2}/{Pt}} - {5./{SiO}_{2}}} = {0.28{{wt}.\%}\left( {{determined}{by}{ICP} - {MS}} \right)}}}{{{activity}({catalyst})} = {{{initial}{experimental}{rate}{of}C_{2}H_{6}{formation}{using}{m{SiO}}_{2}/{Pt}} - {X/{SiO}_{2}}}}{{{{wt}.\%}{Pt}({catalyst})} = {\frac{{mass}{Pt}}{{{mass}{m{SiO}}_{2}/{Pt}} - {X/{SiO}_{2}}}\left( {{determined}{by}{ICP} - {MS}} \right)}}$Gas Chromatography Analysis

Headspace analysis method. Gas Chromatography-Flame Ionization Detector(GC-FID). Gas samples taken from the headspace of the Parr reactor wereanalyzed by GC-FID using an Agilent Technologies 7890A GC systemequipped with a flame ionization detector. A capillary column, AgilentJ&W GS-GasPro [0.32 mm×15 m], was used for compound separation. Sampleswere injected manually using a gas-tight syringe.

Method for analyzing extracted waxes. Gas chromatography-massspectrometry (GC-MS). An Agilent Technologies 7890 A GC system equippedwith an Agilent Technologies 5975 C inert MSD mass spectrometer was usedto analyze the nature of the extracted liquid products. A capillarycolumn, Agilent J&W DB-5ht ((5%-phenyl)-methylpolysiloxane, 0.25 mm×30m×0.1 m) was used for compound separation. Samples were prepared bydissolving 20 mg of the extracted liquid products in 2 mL ofdichloromethane.

Quantification of GC-MS extractable waxes. The composition of theextracted wax fraction, in terms of amounts of each chain length in thesamples, is estimated using our previous reported approach, given herefor convenience: A GC-MS of the ASTM standard was integrated. A plot ofintegrated area vs. carbon number (shown in FIG. 21 ) allows thedetermination of response of all C_(n)(since ASTM standard does notinclude C₁₃, C₁₉, C₂₁, etc.) by interpolation. The regions of C₆-C₂₀ andC₂₀-C₄₀ are linear, but with inequivalent slopes. Therefore, these tworegions were fit separately.

The relative mass ratio as a function of carbon number F(C_(n)) wascalculated by dividing the area of each peak (or calculated peaks forthe appropriate range using the linear fits from FIG. 22 ) by that ofthe C₁₂ (which was arbitrarily chosen—note that this protocol was alsotested with C₂₄ and, expectedly, gives an equivalent scaling factor foreach peak).

${{relative}{mass}{ratio}} = {{F\left( C_{n} \right)} = \frac{{integrated}{peak}{area}{of}C_{n}}{{integrated}{peak}{area}{of}C_{12}}}$

The relative mass ratio for each C_(n) allows the estimation of theGC-MS response for hydrocarbon species as a function of the C_(n). InGC-MS of catalytic mixtures below, the observed integrated intensitiesfor each carbon number are appropriately scaled based on the relativemass ratio F(C_(n)).

${{relative}{intensity}{for}a{carbon}{number}} = {{G\left( C_{n} \right)} = \frac{{observed}{integrated}{intensity}{of}{catalytic}{sample}}{F\left( C_{n} \right)}}$

The percentage of each carbon number is determined by dividing thatcarbon number's relative intensity by the sum of the relativeintensities for all carbon species observed.

${\% C_{n}} = {\frac{G\left( C_{n} \right)}{\underset{6}{\sum\limits^{36}}{G\left( C_{n} \right)}} \times 100\%}$High Temperature—Gel Permeation Chromatography

Number-averaged and weight-averaged molecular weights (M_(n) and M_(w))and molecular weight distributions (M_(w)/M_(n)) of the polymers weredetermined by high-temperature gel permeation chromatography (HT-GPC;Agilent-Polymer Laboratories 220) equipped with RI and viscometerdetectors. Monodisperse polyethylene standards (PSS Polymer StandardsService, Inc.) were used for calibration ranging from ˜330 Da to ˜120kDa. The column set included 3 Agilent PL-Gel Mixed B columns and 1PL-Gel Mixed B guard column. 1,2,4-trichlorobenzene (TCB) containing0.01 wt % 3,5-di-tert-butyl-4-hydroxytoluene (BHT) was chosen as theeluent at a flow rate of 1.0 mL/min at 160° C. The samples were preparedin TCB at a concentration of ˜5.0 mg/mL and heated at 150° C. for 24 hprior to injection.

Catalyst Design and Preparation

Mesoporous shell/catalyst/core (mSiO₂/Pt—X/SiO₂) materials containing PtNPs with average diameters of 1.7 nm (mSiO₂/Pt-1.7/SiO₂), 2.9 nm(mSiO₂/Pt-2.9/SiO₂), and 5 nm (mSiO₂/Pt-5.0/SiO₂) were synthesized toinvestigate the effects of Pt particle size on catalytic polyolefinhydrogenolysis in a confined environment specifically and uniformlylocated at the closed ends of mesopores. All other meso- andnanostructural properties of the mSiO₂/Pt—X/SiO₂ materials areequivalent across the three catalysts, including the 120 nm size of theSiO₂ core, as well as the 2.4 nm diameter and the 120 nm length of themesopores in the silica shell. The uniform meso- and nanoscalearchitecture of these catalysts was created through the syntheticapproach. Common 120 nm monodisperse solid silica spheres, prepared viaa seeded growth process, react with aminopropyl trimethoxysilane to givesurface-functionalized NH₂—SiO₂ spheres. Polyvinylpyrrolidone(PVP)-capped Pt NPs, either 1.7 (±0.3), 2.9 (±0.5), or 5.0 (±1.0) nm indiameter (FIG. 125 ) were immobilized onto the NH₂—SiO₂ spheres(Pt—X/SiO₂, X=1.7, 2.9, or 5.0 nm), then the 120 nm thick,radially-aligned mesoporous silica shell was grown on the Pt—X/SiO₂.Transmission electron microscopy (TEM) reveals that, as desired, thesilica core sizes and mesoporous shell thickness are equivalent acrossthe three samples, and the Pt NPs are localized at the core-shellinterface (FIG. 120 ). Pt NPs are more clearly observed in the sampleprepared with 5.0 nm Pt NPs compared to the smaller Pt NPs, which arenonetheless also clearly localized at the core-shell interface in thehigh-angle annular dark-field scanning transmission electron microscopy(HAADF-STEM) images. The N₂ isotherms from Brunauer-Emmett-Teller (BET)analysis, 943-981 m²/g range of surface areas, 0.81-0.83 cm³/g porevolumes, and 2.4 nm pore diameters calculated from the BJH model wereall nearly identical for three catalysts (FIGS. 126, 127 ). That is, thecharacterization data indicates that the only significant physicaldifference between mSiO₂/Pt-1.7/SiO₂, mSiO₂/Pt-2.9/SiO₂, andmSiO₂/Pt-5.0/SiO₂ is the size of the platinum NPs. We also note that 1.7nm Pt NPs are smaller, on average, than the 2.4 nm mesopore diameter,while the average sizes of the Pt NPs in the other two catalyticmaterials are larger than that of the mesopores.

The active surface area of platinum, which varies between the threemSiO₂/Pt—X/SiO₂ catalytic materials on a per mass basis, should be keptconstant to compare the catalysts' behavior in polyolefin hydrogenolysisreactions. Active Pt in the mSiO₂/Pt—X/SiO₂ materials was estimatedusing the structure-insensitive ethylene hydrogenation reaction (Table13). The mSiO₂/Pt-1.7/SiO₂ material, as expected, catalyzes ethylenehydrogenation with the highest initial activity (95.2 mmol C₂H₆·g_(Pt)⁻¹ s⁻¹), while the activity of mSiO₂/Pt-5.0/SiO₂ (20.5 mmol C₂H₆·g_(Pt)⁻¹ s⁻¹) is the lowest. The higher activity per mass of smaller NP Ptcatalyst is attributed to their higher dispersion. The amount ofcatalyst used for hydrogenolysis reactions was normalized to have thesame number of Pt active sites based on the performance ofmSiO₂/Pt-5.0/SiO₂ in ethylene hydrogenation.

TABLE 13 Reaction rate data for ethylene hydrogenation onmSiO₂/Pt-X/SiO₂ catalysts. Mass of catalyst Loading used for (Pt wt/Activity hydrogenolysis Catalyst silica wt %)^(a) (mmol · g_(Pt) ⁻¹s⁻¹)^(b) (g)^(c) mSiO₂/Pt-1.7/SiO₂ 0.085 95.2 0.0256 mSiO₂/Pt-2.9/SiO₂0.40  37.0 0.0140 mSiO₂/Pt-5.0/SiO₂ 0.28  20.5 0.0360 ^(a)Pt loading foreach mSiO₂/Pt-X/SiO₂ catalyst was measured by inductively coupled plasma(ICP)-MS. ^(b)Reaction conditions: C₂H₄ (10 Torr), H₂ (100 Torr), He(650 Torr), total flow 182.4 mL/min, at 293K, activity calculated basedon ethane production. ^(c)Typical mass of each mSiO₂/Pt-X/SiO₂ catalystsused for polyethylene hydrogenolysis reaction.

Polyethylene hydrogenolysis experiments examining the effects of Pt NPsizes employ these three mSiO₂/Pt—X/SiO₂ catalysts. Typical reactionconditions use linear polyethylene (ca. 3 g PE, M_(n)=20 kDa, M_(w)=90kDa, ρ=0.92 g/mL) and 0.89 MPa of H₂ pressure, heated at 300° C. for6-20 h, in a mechanical impeller-mixed autoclave containing from0.02-0.1 mg Pt, under solvent-free conditions. At the end of eachexperiment, the reactors contained a condensed-phase fraction as well asvolatile species in the headspace. The volatile species were quantifiedby comparison of the mass of condensed phase materials before and afterthe conversion, and the C₁-C₉ hydrocarbons composition of the volatileswas quantified by gas chromatography-flame ionized detector (GC-FID).Soluble species were extracted from the condensed phase using methylenechloride to give a yield of ‘extracted waxes’. The yield is defined asthe weight of waxes divided by the total weight of initially addedpolymer. The quantified composition of the extracted waxes was analyzedby calibrated GC-mass spectrometry (MS), which showed mostly linearC₈˜C₅₀ hydrocarbons. Analysis of the quantities of each fraction andtheir composition, in terms of molecular weight and distribution,provides key insight for comparing performance of the threemSiO₂/Pt—X/SiO₂ catalytic materials. The relative activity of thecatalysts for carbon-carbon bond cleavage is estimated by comparingconversion of PE into small molecules, per surface active site of Ptunder equivalent reaction conditions. The most active catalyst convertsthe largest amount of insoluble solid polymer. The activity of catalyticmaterials may also be compared by analyzing the amounts of volatile andextracted species formed per unit time, with volatile speciescorresponding to more carbon-carbon bond cleavages. For example,formation of 1 g of CH₄ corresponds to a ca. 19-fold greater number ofC—C bond hydrogenolysis steps than 1 g of C₂₀H₄₂; in contrast,conversion of a solid polymeric material with M_(n)−20 kDa into apolymer with M_(n)˜10 kDa corresponds to only one C—C bondhydrogenolysis step, on average. Thus, such assays of catalytic activityare best considered qualitatively.

These two estimates indicate that catalyst activity follows the trendmSiO₂/Pt-1.7/SiO₂>mSiO₂/Pt-2.9/SiO₂>mSiO₂/Pt-5.0/SiO₂ over the course ofthe PE deconstructions (Table 14). For example, based on the amount ofunextracted CH₂Cl₂-insoluble materials after reaction, mSiO₂/Pt-1.7/SiO₂affords 25% conversion of PE after 6 h at 300° C. under 0.89 MPa,whereas only 15% and 6% consumption of PE are observed usingmSiO₂/Pt-2.9/SiO₂ or mSiO₂/Pt-5.0/SiO₂, respectively (FIG. 128 ). Inaddition, mSiO₂/Pt-1.7/SiO₂ gives the most soluble species (16%) and themost gas-phase species (9%), while mSiO₂/Pt-5.0/SiO₂ produces the leastamount of soluble and volatile species (4 and 2%, respectively). Thesedata indicate that the smallest Pt NP catalyst is most active at shortreaction times (at the lowest experimentally accessible conversion underthese conditions). This trend continues over the course of theexperiments. After 12 h, mSiO₂/Pt-1.7/SiO₂ catalyzes the hydrogenolysisof 62% of PE, while mSiO₂/Pt-5.0/SiO₂ gives only 26% conversion.

TABLE 14 Gas, extractable waxes, and insoluble products formed atdifferent reaction time from mSiO₂/Pt-X/SiO₂- catalyzed hydrogenolysis(X =1.7, 2.9, and 5.0 nm).^(a) Reaction Time (h) Catalyst^(a) Product 68 12 20 mSiO₂/Pt- PE (g) 3.029 3.030 3.015 3.007 1.7/SiO₂ gas 0.274(9.1%)  0.349 (11.6%) 0.345 (11.4%) 1.993 (66.3%) liquid 0.476 (15.7%)0.880 (29.0%) 1.523 (50.5%) 1.014 (33.7%) solid 2.279 (75.2%) 1.801(59.4%) 1.147 (38.0%) n.a. mSiO₂/Pt- PE (g) 3.004 3.001 3.002 3.0182.9/SiO₂ gas 0.255 (8.4%)  0.250 (8.3%)  0.360 (12.0%) 0.451 (14.9%)liquid 0.195 (6.4%)  0.611 (20.4%) 1.315 (43.8%) 2.138 (70.8%) solid2.554 (85.2%) 2.139 (71.3%) 1.327 (44.2%) 0.428 (14.2%) mSiO₂/Pt- PE (g)3.066 3.000 3.001 3.066 5.0/SiO₂ gas 0.119 (3.9%)  0.140 (4.7%)  0.259(9.8%)  0.303 (9.8%)  liquid 0.058 (1.9%)  0.255 (8.5%)  0.525 (17.5%)1.892 (61.7%) solid 2.889 (94.2%) 2.604 (86.8%) 2.216 (73.8%) 0.807(26.2%) ^(a)Reaction conditions: 3 g of PE (M_(n) = 20 kDa, M_(w) = 90kDa, ρ = 0.92 g/mL), with 0.0007-0.003 wt. % Pt with respect to PE, 0.89MPa H₂, 300° C.

The yields of extracted waxes also follow the trendmSiO₂/Pt-1.7/SiO₂>mSiO₂/Pt-2.9/SiO₂>mSiO₂/Pt-5.0/SiO₂. After 6 h, forexample, the most active catalyst mSiO₂/Pt-1.7/SiO₂ provides 15.7%extractable waxes, whereas mSiO₂/Pt-2.9/SiO₂ or mSiO₂/Pt-5.0/SiO₂ formonly 6.4% and 1.9%, respectively. In general, the yields of extractablefractions increase during the batch conversion following this trend,until all the unextractable solids are consumed. At that point, theyield of wax decreases. The yield of extracted material obtained usingthe catalyst mSiO₂/Pt-1.7/SiO₂ decreases from 74% after 15 h to 34%after 20 h (FIG. 121 ).

Although more volatile species are formed both initially (6 h) and athigh conversion (20 h) with the mSiO₂/Pt-1.7/SiO₂ catalyst than usingthe larger Pt NP catalysts, following a similar trend as described abovefor extractable waxes, intermediate conversions reveal a powerful,particle-size independent effect on selectivity. Specifically, similarquantities of volatile species are obtained after 12 h with each of thecatalytic materials (ca. 10-12%), even with dramatically differentconversions of polymer.

The mass fraction of volatile species formed using mSiO₂/Pt-1.7/SiO₂ isroughly constant from the first 6 h (at 25% conversion of PE) to 15 h(at 86% conversion of PE), indicating that the solid polymeric materialsundergo selective hydrogenolysis to the extractable waxes over thatportion of the reaction (FIG. 121 ). In addition, the percentage of masscorresponding to volatile species increases from ca. 4% after 6 h (at 5%conversion of PE) to 10% after 12 h (26% conversion of PE) using themSiO₂/Pt-5.0/SiO₂ catalyst. That is, the quantity of volatile speciesobtained from mSiO₂/Pt-1.7/SiO₂ after 6 h is comparable to that ofmSiO₂/Pt-5.0/SiO₂ after 12 h, corresponding to equivalent conversions ofPE (FIGS. 129 and 131 ).

After 20 h, quantitative conversion of polyethylene is achieved withmSiO₂/Pt-1.7/SiO₂. Concurrently, the quantity of volatile speciesdramatically increases, and the fraction of extractable waxesdramatically decreases. This behavior is attributed toover-hydrogenolysis, which involves further conversion of oligomericprimary products into lower value light hydrocarbons. Theover-hydrogenolysis process only becomes dominant once most or all thelong-chain PE is consumed. A test of this idea involves thehydrogenolysis reaction using mSiO₂/Pt-1.7/SiO₂ for 15 h, which a prioriwas postulated to give high yield of extractable waxes and similar(˜10-12%) yields of volatile species at high PE conversion, based onover-hydrolysis at 20 h and the behavior of the other two catalyticmaterials in Table 14. The result from this experiment matches ourexpectation, giving 73.6% yield of extractable waxes with only 12.4% ofgases. Remarkably, all three Pt-sized catalysts give similar massfractions of volatile products at conversions of PE ranging from 25-70%(e.g., 10-12% volatiles), suggesting that the over-hydrogenolysisprocess occurs only at high PE conversion, regardless of the Pt NP size.

mSiO₂/Pt—X/SiO₂ materials also catalyze the hydrogenolysis of a second,smaller polyethylene sample (M_(n)=5.9 kDa, M_(w)=30 kDa) underidentical conditions (ca. 3 g of PE, 300° C., 0.89 MPa H₂) (Table 15). Arelated trend in activity, in which mSiO₂/Pt-1.7/SiO₂ produces the mostliquids and gases (87.3% by mass) after 6 h, while mSiO₂/Pt-2.9/SiO₂ andmSiO₂/Pt-5.0/SiO₂ catalyze the hydrogenolysis of ca. 64% of thepolyethylene to extractable waxes and gases. The distribution of chainlengths in the extracted waxes is similar for the three mSiO₂/Pt-X/SiO₂catalysts. In addition, similar over-hydrogenolysis is observed after 24h using mSiO₂/Pt-1.7/SiO₂ as the catalyst, giving 55% of volatilespecies by mass at that time. This 5.9 kDa M_(n) polyethylene is morereactive than the longer 20 kDa M_(a) polyethylene studied above,producing a higher mass percentage of gases and extractable waxes foreach catalyst under equivalent conditions. Note that the overallcatalytic process involves diffusion and adsorption of chains into thepores, polymer chain adsorption onto Pt, single (or multiple) C—C bondcleavage steps of the chain, and diffusion of the smaller polymerfragments. The relative rates of these steps will affect the overallrate of polymer conversion. Thus, the combined rates of these steps arefaster for the shorter polymer (M_(n)=5.9 kDa) than the longer one(M_(n)=20 kDa).

TABLE 15 Data from mSiO₂/Pt-X/SiO₂-catalyzed hydrogenolysis of the M_(n)= 5.9 kDa PE.^(a) Reactant/ Reaction Time (h) Catalyst Products 6 12 20mSiO_(2/) PE (g) 3.010 3.009 3.013 Pt-1.7/SiO₂ gas 0.886 (29.4%) 1.320(43.8%) 1.664 (55.3%) extracted 1.756 (58.3%) 1.551 (51.5%) 1.349(44.7%) wax solid 0.363 (12.3%) 0.137 (4.5%)  n.a. mSiO₂/ PE (g) 3.0043.002 3.018 Pt-2.9/SiO₂ gas 3.044 3.036 3.010 extracted 0.451 (14.8%)0.446 (14.7%) 0.403 (13.3%) wax solid 1.486 (48.8%) 1.788 (58.8%) 1.925(63.9%) mSiO₂/ PE (g) 3.033 3.019 3.009 Pt-5.0/SiO₂ gas 0.638 (21.3%)0.514 (17.0%) 0.496 (17.1%) extracted 1.272 (41.9%) 1.647 (54.7%) 1.676(55.8%) wax solid 1.112 (36.6 %) 0.859 (28.4%) 0.834 (27.1%)^(a)Reaction conditions: 3 g of PE (M_(n) = 5.9 kDa, M_(w) = 36 kDa, ρ =0.94 g/mL), with 0.0007-0.003 wt. % Pt with respect to PE, H₂ (0.89MPa), 300° C.

The rates of the individual steps, also, could affect the mean chainlength and shape of the distribution of hydrocarbon products in theextractable liquids and waxes. Alternatively, or in addition to akinetic effect, the average length of the platinum NP that is accessibleto the polymer chains could influence the hydrocarbon productdistribution via a templating mechanism, as noted in the Introduction.In such a scenario in which the NP templates the product chain length,1.7 nm and 5.0 nm platinum NPs would give the shortest and longestaverage chain lengths, respectively. Our previous observation that thediameter of the pores in the mesoporous shell influences thedistribution could also come from such kinetic or templating effects.

Given that each of the mSiO₂/Pt—X/SiO₂ catalysts could providehydrocarbon species characteristic of the sizes of their NPs, it wassurprising that instead, the mean and distribution of product chainlength in the extracted wax products are very similar for the threecatalysts and over a wide range of conversions. Comparisons show similarcompositions of the extractable fractions, determined by calibratedGC-MS, obtained after equivalent reaction times, or at similarconversions of solid polymer or having similar percent yields (by mass)of extracted species. Most of the experiments afford soluble hydrocarbonwax products with a mean chain length of ca. C₂₃ and similarly shapeddistributions, as seen by visual inspection (FIG. 122 ) and statisticalanalysis of the histograms. For example, the mean chain length anddistributions of the extracted waxes, obtained using the three PtNP-sized catalysts, are virtually identical from reactions performed toca. 75% conversion of PE (60-70% yield of wax). Moreover, thedistributions of C_(n) chains in the extracted waxes are statisticallyindistinguishable, in terms of the mean product sizes [C₂₃] and betweenthe variances in product size [±7 carbons] as determined by one-wayanalysis of variance (ANOVA).

The distribution of chain lengths in the extracted oil fraction is alsoindependent of conversion throughout the catalytic regime that producesthe most extractable oils. For example, mSiO₂/Pt-1.7/SiO₂ providesC₂₃-centered bell-like distributions of chain lengths as the extractedwax yields range from 30% after shorter reactions (8 h) to 73% afterlonger times (15 h).

At lower conversions obtained with shorter reaction times, theC₂₃-centered distribution is distorted by a lower molecular weightfraction, giving a ‘shoulder’ to the bell-shaped distribution at ˜C₁₄(FIG. 123 , 8 h data and FIG. 124 ). These non-Gaussian lower molecularweight species are likely formed as part of the process that initiallyproduces shorter gas-phase species, and the relative abundance of thesespecies decreases as conversion to a C₂₃-centered distribution of waxproducts increases during the catalytic reactions. Similarly,over-hydrogenolysis, at high conversions that afford large amounts ofgaseous products, also produces a large molar fraction of the extractedproducts with shorter chain lengths (C₉-C₁₅) than observed in theC₂₃-centered distributions from shorter reaction times.

The above observations result from the combined effects of themesoporous shell/active site/core architecture and the high activity ofthe Pt NP sites. Control reactions, in which platinum-free mesoporoussilica shell/solid silica core materials (mSiO₂/SiO₂) are heated with PEunder H₂ at 300° C. for 12 h, result in minimal conversion of the solidpolymer (3.6%) and even less extractable oil product (1.2%; Table 16).

TABLE 16 Gas, extractable waxes, and insoluble products formed frommSiO₂/SiO₂-catalyzcd hydrogenolysis reaction.^(a) PE Reaction Volatileproducts Extracted products Solid residue Catalyst (g) time (h) (%) (%)(%) mSiO₂/SiO₂ 3.043 12 0.074 g (2.4%) 0.0.037 g (1.2%) 2.932 g (96.4%)^(a)Reaction conditions: 3 g of PE (M_(n) = 20 kDa, M_(w) = 90 kDa, ρ =0.92 g/mL), 0.89 MPa H₂, 300° C.

The small amount of extracted liquids contains the signature features ofmSiO₂/Pt/SiO₂ experiments at low conversion, namely a ca. C₂₃-centeredbroad distribution of chain lengths with a shoulder around C₁₄ (FIG.140, 143 ). The similarity of these distributions suggests that abackground reaction, involving interactions of PE and mSiO₂ but not Ptsites, occurs at an early stage of all the conversions. A second controlexperiment shows that the Pt particles supported on the silica core(Pt—X/SiO₂) but lacking the mesoporous silica shell are much lesseffective than the mSiO₂/Pt—X/SiO₂ catalysts. For example, conversion ofPE is only 4.6% after 12 h using Pt-1.7/SiO₂, in comparison to 62%obtained under equivalent conditions with mSiO₂/Pt-1.7/SiO₂. The lowconversion was also obtained using Pt-2.9/SiO₂ (4.3%); and Pt-5.0/SiO₂(13.5%; Table 17). The higher activity of Pt-5.0/SiO₂ compared toPt-1.7/SiO₂ is likely due to less structural changes of the former undercatalytic conditions. The extracted wax products from the Pt—X/SiO₂catalytic materials appear as a flat distribution of chain lengths(FIGS. 179, 182, and 185 ).

TABLE 17 Gas, extracted waxes, and insoluble products formed fromPt-X/SiO₂-catalyzed hydrogenolysis reaction.^(a) Reaction VolatilesExtracted Solid Catalyst PE (g) Time (h) products (%) products (%)residue (%) Pt-1.7/ 3.075 12 0.056 g 0.084 g 2.935 g SiO₂ (1.8%) (2.7%)(95.4%) Pt-2.9/ 3.029 12 0.036 g 0.094 g 2.899 g SiO₂ (1.2%) (3.1%)(95.7%) Pt-5.0/ 3.008 12 0.194 g 0.212 g 3.007 g SiO₂ (6.4%) (7.1%)(86.4%) ^(a)Reaction conditions: 3 g of PE (M_(n) = 20 kDa, M_(w) = 90kDa, ρ = 0.92 g/mL), with 0.0007-0.003 wt. % Pt with respect to PE 0.89MPa H₂, 300° C.

The quantity of volatile species, time-dependence of the mass-basedfractions of products (gases, methylene chloride-extracted waxes, andthe residual solid), GC-FID trace of the sampled headspace, the GC-MS ofextracted waxes, and the carbon number distribution of extracted waxesfor the hydrogenolysis reaction from mSiO₂/Pt-1.7/SiO₂-catalyzed,mSiO₂/Pt-2.9/SiO₂-catalyzed, mSiO₂/Pt-5.0/SiO₂-catalyzed, andmSiO₂/SiO₂-catalyzed hydrogenolysis at various catalyst loadings andreaction times is shown in FIGS. 130, 132-139, 141, 142, 144-181, 183,and 184 .

FIG. 186 shows the bubble wrap plastic waste obtained from backyard aslitter, no pre-cleaning was performed prior to reactions.

The GC-FID trace of the sampled headspace, the GC-MS of extracted waxes,and the carbon number distribution of extracted waxes for thehydrogenolysis reaction using mSiO₂/Pt-1.7/SiO₂ (0.085 Pt wt/silica wt%) as catalyst is shown in FIGS. 187-189 .

The inequivalent behavior of mSiO₂/Pt—X/SiO₂ and Pt—X/SiO₂ catalyticarchitectures are at least partly related to changes in Pt NPs duringhydrogenolysis reactions. The TEM image of catalytic Pt-1.7/SiO₂materials, collected post-catalysis at high conversion (62%) aftermethylene chloride extraction to remove the hydrocarbon products,revealed a significant amount of detached, sintered, and aggregated PtNPs. In contrast, TEM of mSiO₂/Pt-1.7/SiO₂ collected on as-synthesizedand post-reaction materials indicates that Pt NPs are located at theshell/core interface even after mixing in melted PE, hydrogenolysistreatment, and extraction and separation from organic products with noapparent aggregation (FIG. 128 ). This contrast further highlights theimportance of the architecture of mSiO₂/Pt—X/SiO₂ in which confinementof Pt NPs prevents aggregation, and the mSiO₂ overcoat prevents thedetaching of particles from the support.

Influence of the mSiO₂/Pt—X/SiO₂ catalytic architecture on PEhydrogenolysis. The mSiO₂/Pt—X/SiO₂ architecture is responsible for thevery efficiently catalyzed PE conversions, which require very lowplatinum loading. The three mSiO₂/Pt—X/SiO₂ catalysts operateeffectively at 0.7-3.4×10⁻⁵ g Pt/g PE, converting M_(a)=20 kDa into longoligomeric hydrocarbon waxes in over 70% yield after 15-20 h at 300° C.With these catalysts and low Pt loading, PE with M_(n) of 5.9 kDa isalso converted into waxy hydrocarbons in 40-60% yield within 6 h. Forcomparison, the Pt-1.7/SiO₂ catalyst, composed of identical colloidal PtNPs similarly immobilized on identical Stöber SiO₂ core as themSiO₂/Pt/SiO₂, gives only 4.6% conversion with 0.7-1.4×10⁻⁵ g Pt/g PEunder comparable conditions. Although the poor performance of Pt/SiO₂ isat least partly associated with catalyst degradation, an activesite-immobilized and highly selective catalyst with Pt NPs on itsexternal surface, 5c-Pt/SrTiO₃, also requires 2.4×10⁻³ g Pt/g PE toreduce M_(n) from 8.15 kDa to 2.15 kDa (in 97% yield) after 24 h at 300°C. under 1.17 MPa of H₂, and produces a desirable M_(n) of 600 Da after96 h. A Ru/C catalyst needs 1.3×10⁻² g Ru/g PE at the low temperature of200° C. and 2 MPa of H₂ to convert PE with M_(n) of 1.7 kDa into 45%yield of liquid alkane distributions centered at C₁₆. Alternatively,1.5×10⁻³ g Ru/CeO₂/g low density polyethylene (LDPE) converts M_(n) of1.7 kDa into 90% yield of C₅-C₄₅ liquids and waxes at 240° C. after 8 hunder 6 MPa of H₂. The ability of mSiO₂/Pt—X/SiO₂ materials to beeffective at low Pt loading is a consequence of high reactivity forcarbon-carbon bond cleavage in polyolefins and long lifetime. The latterfeature is further supported by this catalyst remaining equivalentlyeffective and selective after multiple recovery and re-use cycles. Weattribute the long lifetime of the catalyst, under these reactionconditions, to effects of both architecture and the synthetic approach.The isolation of individual Pt NPs in the bottom of a mesoporous silicachannel limits their dissociation from the silica support duringcatalytic hydrogenolysis. Because rates of hydrocarbon hydrogenolysisare structure-sensitive, sintering into larger Pt NPs will have anoutsized negative effect on deactivation. We also noted above that 1.7nm Pt NPs are smaller than the 2.4 nm diameter mesoporous channels;however, release of Pt NPs from mSiO₂/Pt-1.7/SiO₂ was not detected, incontrast to their observed release from the silica surface of Pt—X/SiO₂during catalysis. Likely, the Pt NPs are embedded into the walls of themesoporous silica shell. Thus, the persistent confinement of theseparticles at the shell/core interface needed for long catalyst lifetimeoriginates from not only geometric factors. Likely, the growth of themSiO₂ shell also chemically immobilizes Pt NPs in the catalyticmaterial.

The mSiO₂/Pt—X/SiO₂ architecture also appears to impart high activityfor these catalytic conversions. Although precise rate constants ofcarbon-carbon bond cleavage are not readily measured, due to thethousands of possible individual steps associated with many inequivalentbonds in the distribution of species in the reactor, the relativeactivities of these catalysts may be assessed qualitatively. Oneindicator of high activity is the small amount of Pt in the reactor thatis capable of converting PE into small molecules in a relatively shortamount of time. The long catalyst lifetime noted above contributes tothe apparent high activity of this qualitative assessment because theanalysis is not performed at low conversion (where catalyst deactivationwould be avoided); thus, comparisons of activity with Pt—X/SiO₂ havelittle value. Nonetheless, comparisons of metal loading in catalyststhat transform a large fraction of the polyolefins, identified above forhydrogenolysis catalysts, suggest that the Pt centers in mSiO₂/Pt—X/SiO₂are especially active. Moreover, the active sites in this material areat the closed end of 120 nm-long mesopores, which require polymers toenter and translocate through the pores to reach the Pt NPs. These stepsare not rate-controlling, as evidenced by the shorter reaction times toreach equivalent liquid yields using catalysts with smaller Pt NPs,probably because the pores are constantly filled with polymer chainsunder these conditions. Interestingly, the shorter reaction times neededfor full conversion of smaller (M_(n)=5.9 kDa) PE suggests that chainlength influences the overall reaction rate, perhaps as a result of morefavorable matching of polymer and pore lengths. The rate ofcarbon-carbon bond cleavage at a particular catalytic site should bevery similar for all H₂C—CH₂ linkages in hydrocarbon chains, whereasadsorption or translocation in the pores could be affected by themolecular mass of a chain.

The architecture of the mSiO₂/Pt—X/SiO₂ catalysts is also responsiblefor high selectivity and high yields of an approximately bell-shapeddistribution of the extracted wax products. As the PE deconstructionproceeds over time, the yield of each species in the distribution of theextracted wax products increases. At high conversion (ca. 85%),selectivity for the waxy distribution with mSiO₂/Pt-1.7-SiO₂ is 85%,calculated as the mass of waxy liquids/total mass of deconstructedproducts (waxy liquids and gas). The selectivities of bothmSiO₂/Pt-2.9/SiO₂ at 85% conversion or mSiO₂/Pt-5.0/SiO₂ at 72%conversion are also ca. 85% for the statically indistinguishable waxyproduct distribution. That is, the three sized Pt NP catalysts provideequivalent chain-length distribution of the products and equivalentselectivity for those distributions. This characteristic selectiveproduction of a certain range of hydrocarbon oligomers is noticeablyabsent from the control catalyst (Pt—X/SiO₂) at any stage of conversion.As noted in the Introduction, the average chain length of the productsis affected by the characteristics of the mesoporous silica shell in themSiO₂/Pt/SiO₂ catalysts. On the basis of this behavior and extensivesolid-state ¹³C NMR studies of conformational and dynamic behavior ofabsorbed polyethylene, we proposed that the polymer chains could onlythread in a specific manner to reach the active Pt site. Thus, the C—Cbond cleavage in a polymeric chain is confined to a certain averagelength, resulting in selective distributions of alkanes. That is, themesoporous architecture confers selectivity, templating a narrow rangeof products from hydrogenolysis, rather than the NP sites where thecarbon-carbon bond cleavage occurs.

Influence of the Pt NPs on hydrogenolysis. Time-dependence of PEconsumption, time-dependence of wax yields indicate faster reactions forsmaller Pt NPs in mSiO₂/Pt—X/SiO₂ compared to larger ones, a signatureof a structure-sensitive catalytic reaction. For example, 29% yield ofextracted wax is obtained after 8 h using mSiO₂/Pt-1.7/SiO₂, whereasonly 8.5% yield is produced by mSiO₂/Pt-5.0/SiO₂ after the same amountof time. Similarly, at high conversion, ˜75% yield of extracted wax isobtained with mSiO₂/Pt-1.7/SiO₂ after 15 h, whereas mSiO₂/Pt-2.9/SiO₂requires 20 h. The shorter reaction times for conversions of equivalentamounts of PE to comparable distributions of smaller hydrocarbon chainsis a qualitative indicator of higher catalytic rates for the smallerNPs, from experiments using equivalent platinum active sites in thereactor.

The rate of PE hydrogenolysis catalyzed by the active sites in smallerPt NPs is higher than that of sites in larger Pt NPs. In contrast, thesimilar rates for the small and large Pt NPs as well as Pt surfaces is ahallmark of structure insensitive reactions. Thus, this qualitativeassessment reveals that PE hydrogenolysis rates are increased withgreater proportions of edge and corner sites compared to facets in thePt NPs, and we infer that hydrogenolysis catalysis using mSiO₂/Pt—X/SiO₂is a structure-sensitive catalytic reaction. Hydrogenolysis of lightlinear, branched, and cyclic alkanes have been demonstrated to bestructure sensitive on metal surfaces, whose activity (and selectivity)varies with the exposed single crystal facet. This structure sensitivitynaturally transfers to NP catalysts, because the distribution of surfaceatoms at the facets changes with the size of the NP. For example, therate of ethane hydrogenolysis, in terms of turnover frequency (TOF), for1.7 nm Pt/SBA-15 (1.2×10⁻² s⁻¹) is double compared to that of 2.9 nmPt/SBA-15 (0.6×10⁻² s⁻¹). This trend, involving smaller metal NPscharacterized by faster reactions, is observed for thesesilica-supported Pt NPs operating under gas-solid conditions, whilelarger NPs on other supports (such as Pt/Al₂O₃) have been shown to havehigher activity than smaller NPs. Small Pt NPs, prepared by one ALDcycle in the 1c-Pt/SrTiO₃ catalyst, have higher activity for PEhydrogenolysis than medium and large Pt NPs, revealing that Pt NP sizeeffect and associated structure sensitivity is also important incondensed phase C—C bond hydrogenolysis.

Structure sensitivity is often also manifested in terms of selectivity.For example, larger Pt NPs catalyze hydrogenolysis of small hydrocarbonsin solid-gas reactions to give more branched products than linear ones,favoring cleavage of carbon-carbon bonds of secondary carbons over thoseinvolving tertiary carbons. In 1c-Pt/SrTiO₃-catalyzed hydrogenolysis ofHDPE in the condensed phase, the higher rate of C—C bond cleavage alsoprovides more light hydrocarbon products and gives poor selectivity tohigh quality liquids than in reactions using the larger Pt NPs in5c-Pt/SrTiO₃. As noted above, remarkably, the selectivity of PEhydrogenolysis catalyzed by small, medium, and larger Pt NPs inmSiO₂/Pt—X/SiO₂ is independent of the particle size. As an additionalcomparison, similar amounts of volatiles species (˜9%) and extractedwaxes (˜18%) are obtained at similar conversions for the threecatalysts. This result reveals that smaller Pt NPs in mSiO₂/Pt-1.7/SiO₂form similar amounts of light hydrocarbon products as inmSiO₂/Pt-5.0/SiO₂, in contrast to the behavior of Pt/SrTiO₃ catalysts.

The synthesis of smaller (1.7 nm), intermediate (2.9 nm), and larger(5.0 nm) Pt NPs in the identical mSiO₂/Pt—X/SiO₂ architecture provides afamily of efficient, highly active, and highly selective catalysts withcharacteristic features and excellent behavior, across the three Pt NPsizes, in polyethylene hydrogenolysis. The smallest Pt NP is smallerthan the 2.4 nm diameter of the mesopore in mSiO₂/Pt—X/SiO₂, while thelargest Pt NP is larger than the pore diameter. The conversionscatalyzed by these catalysts proceed in three stages. The firstapproximately 25% of PE conversion is poorly selective for themSiO₂/Pt—X/SiO₂ catalysts, giving approximately 65% (by mass) ofproducts as waxy hydrocarbons. The second stage, involving another60-75% conversion of the PE, is highly selective for a narrowC₂₃-centered distribution of the desired wax-like products. Thisdistribution is templated by the mSiO₂/Pt-X/SiO₂ architecture, ratherthan by the size of the Pt NPs. Adsorption of PE chains into mesoporeslimits conformations to affect the average product chain length. Thisprominent pore template effect is further demonstrated by theindependence of the C₂₃-based bell-shaped distribution of the extractedwax products to Pt NP size as well as reaction time or conversion (priorto over-hydrogenolysis). This pore-templated cleavage phenomenon wasalso observed in mSiO₂/Pt-5.0/SiO₂-catalyzed hydrogenolysis of PE at250° C., which showed features consistent with a processive mechanism.We note that the present conditions (300° C.) result in decreased M_(n)of the residual PE over the reaction, which is not consistent withhighly processive behavior. Thus, the pore-templated carbon-carbon bondcleavage, which is a component of the processive mechanism, alsofunctions in related processes with a low degree of processivity. Thepresent study also indicates that the size of the exposed Pt surface,dictated either by Pt NP size or pore diameter of the mesoporous shell,is unlikely to be responsible for selecting the average chain-length ofthe product.

Once nearly all of the PE is consumed, undesired over-hydrogenolysis ofthe wax into volatile species is observed in the third stage. At thisstage, the average carbon number decreases from the C₂₃-centereddistribution as the reaction proceeds. Thus, mSiO₂/Pt—X/SiO₂ is not onlyselective for hydrogenolysis of PE to waxes but also remarkablyselective for hydrogenolysis of PE in the presence of a large amount ofC₂₃-centered waxes. The three stages of PE hydrogenolysis occur fasterwith smaller Pt NPs than with larger ones, corresponding to an increasein catalytic rate without significantly diminishing selectivity.

Upcycling Post-Consumed Bubble Wrap by Pt-catalyzed Hydrogenolysis

The products formed (gas, extracted waxes, and insoluble products) frommSiO₂/Pt-1.7/SiO₂-catalyzed hydrogenolysis reaction of post-consumerbubble wrap is shown in Table 18.

TABLE 18 Volatile Extracted Solid Time products wax residue Catalyst PE(g) (h) (%) products (%) (%) mSiO₂/Pt-1.7/SiO₂ 3.002 12 0.310 g 0.865 g1.827 g (10.3%) (28.8%) (60.9%) Conditions: 0.0007 wt/PE wt % heated inthe reactor for 12 h at 300° C. under H₂ (at 0.89 MPa).

Although preferred embodiments have been depicted and described indetail herein, it will be apparent to those skilled in the relevant artthat various modifications, additions, substitutions, and the like canbe made without departing from the spirit of the invention and these aretherefore considered to be within the scope of the invention as definedin the claims which follow.

What is claimed:
 1. A catalyst comprising: a silica core having an outersurface; a mesoporous silica shell having an outer surface and an innersurface with the inner surface being inside the outer surface of saidmesoporous silica shell proximate to and surrounding the outer surfaceof said silica core, wherein the outer surface of the mesoporous silicashell has openings leading to pores within the mesoporous silica shellwhich extend toward the outer surface of said silica core; andcatalytically active metal nanoparticles positioned within the poresproximate to said core, wherein said catalytic metal nanoparticlescomprise about 0.0001 wt % to about 1.0 wt % of the catalyst and whereinthe catalytic metal nanoparticles have a mean particle diameter of about1 nm to about 4 nm.
 2. The catalyst of claim 1, wherein the silica corefurther comprises a functional group selected from the group consistingof amines, carboxylic acids, alcohols, thiols, phosphorus, andcombinations thereof.
 3. The catalyst of claim 2, wherein the functionalgroup is an amine.
 4. The catalyst of claim 1, wherein the catalyticmetal nanoparticles are positioned on the outer surface of the silicacore.
 5. The catalyst of claim 1, wherein the catalyst has a meanparticle diameter of about 100 nm to about 1000 nm.
 6. The catalyst ofclaim 5, wherein the metal for the catalytic metal nanoparticle isplatinum.
 7. The catalyst of claim 1, wherein the silica core has a meanparticle diameter of about 50 nm to about 500 nm.
 8. The catalyst ofclaim 1, wherein the metal for the catalytic metal nanoparticle isselected from the group consisting of nickel, palladium, platinum,cobalt, rhodium, iridium, iron, ruthenium, osmium, manganese, rhenium,chromium, molybdenum, tungsten, and combinations thereof.
 9. Thecatalyst of claim 1, wherein the mesoporous silica shell has a thicknessof about 50 nm to about 500 nm.
 10. The catalyst of claim 1, wherein themesoporous silica shell has a pore diameter of about 1 nm to about 10nm.
 11. The catalyst of claim 1, wherein the pores have a length ofabout the thickness of the mesoporous silica shell measured between itsinner and outer surfaces.
 12. A process for catalyticallyhydrogenolysizing a polyolefinic polymer, said process comprising:providing a polyolefinic polymer and subjecting said polyolefinicpolymer to a hydrogenolysis reaction in the presence of a catalyst tocleave the polymer into hydrocarbon segments, wherein the catalystcomprises: a silica core having an outer surface; a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said silica core,wherein the outer surface of the mesoporous silica shell has openingsleading to pores within the mesoporous silica shell which extend towardthe outer surface of said silica core; and catalytic metal nanoparticlespositioned within the pores proximate to said core to cleave saidpolyolefinic polymer entering said mesoporous silica shell through theopenings into hydrocarbon segments, wherein the catalytic metalnanoparticles have a mean particle diameter of about 1 nm to about 4 nm.13. The process of claim 12, wherein the silica core further comprises afunctional group selected from the group consisting of amines,carboxylic acids, alcohols, thiols, phosphorus, and combinationsthereof.
 14. The process of claim 13, wherein the functional group is anamine.
 15. The process of claim 12, wherein the catalytic metalnanoparticles are positioned on the outer surface of the silica core.16. The process of claim 12, wherein the catalyst has a mean particlediameter of about 100 nm to about 1000 nm.
 17. The process of claim 12,wherein the silica core has a mean particle diameter of about 50 nm toabout 500 nm.
 18. The process of claim 12, wherein the metal for thecatalytic metal nanoparticle is selected from the group consisting ofnickel, palladium, platinum, cobalt, rhodium, iridium, iron, ruthenium,osmium, manganese, rhenium, chromium, molybdenum, tungsten, andcombinations thereof.
 19. The process of claim 18, wherein the metal forthe catalytic metal nanoparticle is platinum.
 20. The process of claim12, wherein the catalytic metal nanoparticle comprises about 0.0001 wt %to about 1.0 wt % of the catalyst.
 21. The process of claim 12, whereinthe mesoporous silica shell has a thickness of about 50 nm to about 500nm.
 22. The process of claim 12, wherein the mesoporous silica shell hasa pore diameter of about 1 nm to about 10 nm.
 23. The process of claim12, wherein the pores have a length of about the thickness of themesoporous silica shell measured between its inner and outer surfaces.24. The process of claim 12, wherein said polyolefinic polymer isselected from the group consisting of physical mixtures of polymers,polymeric blends, copolymers, block copolymers, graft copolymers, andcombinations thereof.
 25. The process of claim 12, wherein saidpolyolefinic polymer is selected from the group consisting of highdensity polyethylene, isostatic polypropylene, medium densitypolyethylene, low density polyethylene, linear low density polyethylene,ultra high molecular weight polyethylene, and combinations thereof. 26.The process of claim 25, wherein said polyolefinic polymer is highdensity polyethylene having a number average molecular weight (M_(n)) of5000-100000 Da.
 27. The process of claim 12, wherein said polyolefinicpolymer has a longitudinal extent between opposed ends and saidsubjecting said polyolefinic polymer to a hydrogenolysis reactioncomprises: extending an end of said polyolefinic polymer through theopenings and into the pores of said mesoporous silica shell and cleavingsaid polyolefinic polymer into hydrocarbon segments in the pores usingthe catalytic metal nanoparticle.
 28. The process of claim 12, whereinthe pores have dimensions selected to produce a size distribution of thehydrocarbon segments as a result of hydrogenolysis.
 29. The process ofclaim 12, wherein the pores have a diameter selected to permit a lengthof said polyolefinic polymer to enter the pores which yield a particularsegment length as a result of hydrogenolysis.
 30. The process of claim12, wherein said subjecting is carried out at a pressure about 1 psi toabout 1000 psi.
 31. The process of claim 12, wherein said subjecting iscarried out at a temperature of about 150° C. to about 400° C.
 32. Amethod of preparing a catalyst comprising: adding a functional group toa silica core having an outer surface to produce a functionalized silicacore; contacting the functionalized silica core with a plurality ofcatalytic metal nanoparticles having a mean particle diameter of about 1nm to about 4 nm, wherein the catalytic metal nanoparticles adhere tothe surface of the functionalized silica core to produce afunctionalized silica core supported catalytic metal nanoparticles;contacting the functionalized silica core supported catalytic metalnanoparticles with a silicon compound to produce a mesoporous silicashell having an outer surface and an inner surface with the innersurface being inside the outer surface of said mesoporous silica shellproximate to and surrounding the outer surface of said functionalizedsilica core supported catalytic metal nanoparticles, wherein the outersurface of the mesoporous silica shell has openings leading to poreswithin the mesoporous silica shell which extend toward the outer surfaceof said functionalized silica core supported catalytic metalnanoparticles.
 33. The method of claim 32, wherein functional group isselected from the group consisting of: amines, carboxylic acids,alcohols, thiols, phosphorus, and combinations thereof.
 34. The methodof claim 33, wherein the functional group is an amine.
 35. The method ofclaim 32, wherein the catalyst has a mean particle diameter of about 100nm to about 1000 nm.
 36. The method of claim 32, wherein the silica corehas a mean particle diameter of about 50 nm to about 500 nm.
 37. Themethod of claim 32, wherein the metal for the plurality of catalyticmetal nanoparticles is selected from the group consisting of nickel,palladium, platinum, cobalt, rhodium, iridium, iron, ruthenium, osmium,manganese, rhenium, chromium, molybdenum, tungsten, and combinationsthereof.
 38. The method of claim 37, wherein the metal for the pluralityof catalytic metal nanoparticles is platinum.
 39. The method of claim32, wherein the plurality of catalytic metal nanoparticles comprisesabout 0.0001 wt % to about 1.0 wt % of the catalyst.
 40. The method ofclaim 32, wherein the mesoporous silica shell has a thickness of about50 nm to about 500 nm.
 41. The method of claim 32, wherein themesoporous silica shell has a pore diameter of about 1 nm to about 10nm.
 42. The catalyst of claim 32, wherein the pores have a length ofabout the thickness of the mesoporous silica shell measured between itsinner and outer surfaces.
 43. The method of claim 32, wherein thesilicon compound is selected from the group consisting of:orthosilicates, metasilicates, pyrosilicates, and combinations thereof.